548 lines
15 KiB
C
548 lines
15 KiB
C
//========================================================================
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// This is an example program for the GLFW library
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//
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// The program uses a "split window" view, rendering four views of the
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// same scene in one window (e.g. useful for 3D modelling software). This
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// demo uses scissors to separate the four different rendering areas from
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// each other.
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//
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// (If the code seems a little bit strange here and there, it may be
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// because I am not a friend of orthogonal projections)
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//========================================================================
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#define GLAD_GL_IMPLEMENTATION
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#include <glad/gl.h>
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#define GLFW_INCLUDE_NONE
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#include <GLFW/glfw3.h>
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#if defined(_MSC_VER)
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// Make MS math.h define M_PI
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#define _USE_MATH_DEFINES
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#endif
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#include <math.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <linmath.h>
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//========================================================================
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// Global variables
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//========================================================================
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// Mouse position
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static double xpos = 0, ypos = 0;
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// Window size
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static int width, height;
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// Active view: 0 = none, 1 = upper left, 2 = upper right, 3 = lower left,
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// 4 = lower right
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static int active_view = 0;
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// Rotation around each axis
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static int rot_x = 0, rot_y = 0, rot_z = 0;
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// Do redraw?
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static int do_redraw = 1;
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//========================================================================
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// Draw a solid torus (use a display list for the model)
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//========================================================================
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#define TORUS_MAJOR 1.5
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#define TORUS_MINOR 0.5
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#define TORUS_MAJOR_RES 32
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#define TORUS_MINOR_RES 32
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static void drawTorus(void)
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{
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static GLuint torus_list = 0;
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int i, j, k;
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double s, t, x, y, z, nx, ny, nz, scale, twopi;
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if (!torus_list)
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{
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// Start recording displaylist
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torus_list = glGenLists(1);
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glNewList(torus_list, GL_COMPILE_AND_EXECUTE);
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// Draw torus
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twopi = 2.0 * M_PI;
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for (i = 0; i < TORUS_MINOR_RES; i++)
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{
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glBegin(GL_QUAD_STRIP);
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for (j = 0; j <= TORUS_MAJOR_RES; j++)
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{
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for (k = 1; k >= 0; k--)
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{
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s = (i + k) % TORUS_MINOR_RES + 0.5;
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t = j % TORUS_MAJOR_RES;
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// Calculate point on surface
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x = (TORUS_MAJOR + TORUS_MINOR * cos(s * twopi / TORUS_MINOR_RES)) * cos(t * twopi / TORUS_MAJOR_RES);
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y = TORUS_MINOR * sin(s * twopi / TORUS_MINOR_RES);
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z = (TORUS_MAJOR + TORUS_MINOR * cos(s * twopi / TORUS_MINOR_RES)) * sin(t * twopi / TORUS_MAJOR_RES);
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// Calculate surface normal
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nx = x - TORUS_MAJOR * cos(t * twopi / TORUS_MAJOR_RES);
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ny = y;
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nz = z - TORUS_MAJOR * sin(t * twopi / TORUS_MAJOR_RES);
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scale = 1.0 / sqrt(nx*nx + ny*ny + nz*nz);
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nx *= scale;
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ny *= scale;
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nz *= scale;
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glNormal3f((float) nx, (float) ny, (float) nz);
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glVertex3f((float) x, (float) y, (float) z);
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}
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}
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glEnd();
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}
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// Stop recording displaylist
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glEndList();
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}
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else
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{
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// Playback displaylist
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glCallList(torus_list);
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}
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}
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//========================================================================
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// Draw the scene (a rotating torus)
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//========================================================================
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static void drawScene(void)
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{
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const GLfloat model_diffuse[4] = {1.0f, 0.8f, 0.8f, 1.0f};
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const GLfloat model_specular[4] = {0.6f, 0.6f, 0.6f, 1.0f};
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const GLfloat model_shininess = 20.0f;
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glPushMatrix();
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// Rotate the object
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glRotatef((GLfloat) rot_x * 0.5f, 1.0f, 0.0f, 0.0f);
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glRotatef((GLfloat) rot_y * 0.5f, 0.0f, 1.0f, 0.0f);
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glRotatef((GLfloat) rot_z * 0.5f, 0.0f, 0.0f, 1.0f);
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// Set model color (used for orthogonal views, lighting disabled)
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glColor4fv(model_diffuse);
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// Set model material (used for perspective view, lighting enabled)
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glMaterialfv(GL_FRONT, GL_DIFFUSE, model_diffuse);
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glMaterialfv(GL_FRONT, GL_SPECULAR, model_specular);
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glMaterialf(GL_FRONT, GL_SHININESS, model_shininess);
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// Draw torus
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drawTorus();
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glPopMatrix();
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}
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//========================================================================
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// Draw a 2D grid (used for orthogonal views)
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//========================================================================
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static void drawGrid(float scale, int steps)
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{
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int i;
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float x, y;
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mat4x4 view;
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glPushMatrix();
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// Set background to some dark bluish grey
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glClearColor(0.05f, 0.05f, 0.2f, 0.0f);
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glClear(GL_COLOR_BUFFER_BIT);
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// Setup modelview matrix (flat XY view)
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{
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vec3 eye = { 0.f, 0.f, 1.f };
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vec3 center = { 0.f, 0.f, 0.f };
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vec3 up = { 0.f, 1.f, 0.f };
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mat4x4_look_at(view, eye, center, up);
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}
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glLoadMatrixf((const GLfloat*) view);
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// We don't want to update the Z-buffer
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glDepthMask(GL_FALSE);
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// Set grid color
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glColor3f(0.0f, 0.5f, 0.5f);
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glBegin(GL_LINES);
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// Horizontal lines
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x = scale * 0.5f * (float) (steps - 1);
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y = -scale * 0.5f * (float) (steps - 1);
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for (i = 0; i < steps; i++)
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{
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glVertex3f(-x, y, 0.0f);
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glVertex3f(x, y, 0.0f);
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y += scale;
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}
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// Vertical lines
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x = -scale * 0.5f * (float) (steps - 1);
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y = scale * 0.5f * (float) (steps - 1);
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for (i = 0; i < steps; i++)
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{
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glVertex3f(x, -y, 0.0f);
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glVertex3f(x, y, 0.0f);
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x += scale;
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}
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glEnd();
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// Enable Z-buffer writing again
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glDepthMask(GL_TRUE);
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glPopMatrix();
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}
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//========================================================================
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// Draw all views
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//========================================================================
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static void drawAllViews(void)
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{
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const GLfloat light_position[4] = {0.0f, 8.0f, 8.0f, 1.0f};
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const GLfloat light_diffuse[4] = {1.0f, 1.0f, 1.0f, 1.0f};
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const GLfloat light_specular[4] = {1.0f, 1.0f, 1.0f, 1.0f};
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const GLfloat light_ambient[4] = {0.2f, 0.2f, 0.3f, 1.0f};
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float aspect;
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mat4x4 view, projection;
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// Calculate aspect of window
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if (height > 0)
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aspect = (float) width / (float) height;
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else
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aspect = 1.f;
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// Clear screen
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glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
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glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
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// Enable scissor test
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glEnable(GL_SCISSOR_TEST);
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// Enable depth test
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glEnable(GL_DEPTH_TEST);
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glDepthFunc(GL_LEQUAL);
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// ** ORTHOGONAL VIEWS **
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// For orthogonal views, use wireframe rendering
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glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
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// Enable line anti-aliasing
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glEnable(GL_LINE_SMOOTH);
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glEnable(GL_BLEND);
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glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
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// Setup orthogonal projection matrix
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glMatrixMode(GL_PROJECTION);
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glLoadIdentity();
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glOrtho(-3.0 * aspect, 3.0 * aspect, -3.0, 3.0, 1.0, 50.0);
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// Upper left view (TOP VIEW)
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glViewport(0, height / 2, width / 2, height / 2);
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glScissor(0, height / 2, width / 2, height / 2);
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glMatrixMode(GL_MODELVIEW);
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{
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vec3 eye = { 0.f, 10.f, 1e-3f };
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vec3 center = { 0.f, 0.f, 0.f };
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vec3 up = { 0.f, 1.f, 0.f };
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mat4x4_look_at( view, eye, center, up );
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}
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glLoadMatrixf((const GLfloat*) view);
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drawGrid(0.5, 12);
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drawScene();
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// Lower left view (FRONT VIEW)
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glViewport(0, 0, width / 2, height / 2);
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glScissor(0, 0, width / 2, height / 2);
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glMatrixMode(GL_MODELVIEW);
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{
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vec3 eye = { 0.f, 0.f, 10.f };
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vec3 center = { 0.f, 0.f, 0.f };
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vec3 up = { 0.f, 1.f, 0.f };
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mat4x4_look_at( view, eye, center, up );
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}
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glLoadMatrixf((const GLfloat*) view);
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drawGrid(0.5, 12);
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drawScene();
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// Lower right view (SIDE VIEW)
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glViewport(width / 2, 0, width / 2, height / 2);
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glScissor(width / 2, 0, width / 2, height / 2);
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glMatrixMode(GL_MODELVIEW);
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{
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vec3 eye = { 10.f, 0.f, 0.f };
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vec3 center = { 0.f, 0.f, 0.f };
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vec3 up = { 0.f, 1.f, 0.f };
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mat4x4_look_at( view, eye, center, up );
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}
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glLoadMatrixf((const GLfloat*) view);
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drawGrid(0.5, 12);
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drawScene();
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// Disable line anti-aliasing
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glDisable(GL_LINE_SMOOTH);
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glDisable(GL_BLEND);
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// ** PERSPECTIVE VIEW **
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// For perspective view, use solid rendering
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glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
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// Enable face culling (faster rendering)
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glEnable(GL_CULL_FACE);
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glCullFace(GL_BACK);
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glFrontFace(GL_CW);
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// Setup perspective projection matrix
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glMatrixMode(GL_PROJECTION);
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mat4x4_perspective(projection,
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65.f * (float) M_PI / 180.f,
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aspect,
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1.f, 50.f);
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glLoadMatrixf((const GLfloat*) projection);
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// Upper right view (PERSPECTIVE VIEW)
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glViewport(width / 2, height / 2, width / 2, height / 2);
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glScissor(width / 2, height / 2, width / 2, height / 2);
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glMatrixMode(GL_MODELVIEW);
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{
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vec3 eye = { 3.f, 1.5f, 3.f };
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vec3 center = { 0.f, 0.f, 0.f };
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vec3 up = { 0.f, 1.f, 0.f };
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mat4x4_look_at( view, eye, center, up );
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}
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glLoadMatrixf((const GLfloat*) view);
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// Configure and enable light source 1
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glLightfv(GL_LIGHT1, GL_POSITION, light_position);
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glLightfv(GL_LIGHT1, GL_AMBIENT, light_ambient);
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glLightfv(GL_LIGHT1, GL_DIFFUSE, light_diffuse);
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glLightfv(GL_LIGHT1, GL_SPECULAR, light_specular);
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glEnable(GL_LIGHT1);
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glEnable(GL_LIGHTING);
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// Draw scene
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drawScene();
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// Disable lighting
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glDisable(GL_LIGHTING);
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// Disable face culling
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glDisable(GL_CULL_FACE);
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// Disable depth test
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glDisable(GL_DEPTH_TEST);
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// Disable scissor test
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glDisable(GL_SCISSOR_TEST);
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// Draw a border around the active view
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if (active_view > 0 && active_view != 2)
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{
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glViewport(0, 0, width, height);
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glMatrixMode(GL_PROJECTION);
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glLoadIdentity();
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glOrtho(0.0, 2.0, 0.0, 2.0, 0.0, 1.0);
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glMatrixMode(GL_MODELVIEW);
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glLoadIdentity();
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glTranslatef((GLfloat) ((active_view - 1) & 1), (GLfloat) (1 - (active_view - 1) / 2), 0.0f);
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glColor3f(1.0f, 1.0f, 0.6f);
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glBegin(GL_LINE_STRIP);
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glVertex2i(0, 0);
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glVertex2i(1, 0);
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glVertex2i(1, 1);
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glVertex2i(0, 1);
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glVertex2i(0, 0);
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glEnd();
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}
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}
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//========================================================================
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// Framebuffer size callback function
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//========================================================================
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static void framebufferSizeFun(GLFWwindow* window, int w, int h)
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{
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width = w;
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height = h > 0 ? h : 1;
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do_redraw = 1;
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}
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//========================================================================
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// Window refresh callback function
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//========================================================================
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static void windowRefreshFun(GLFWwindow* window)
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{
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drawAllViews();
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glfwSwapBuffers(window);
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do_redraw = 0;
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}
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//========================================================================
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// Mouse position callback function
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//========================================================================
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static void cursorPosFun(GLFWwindow* window, double x, double y)
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{
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int wnd_width, wnd_height, fb_width, fb_height;
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double scale;
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glfwGetWindowSize(window, &wnd_width, &wnd_height);
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glfwGetFramebufferSize(window, &fb_width, &fb_height);
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scale = (double) fb_width / (double) wnd_width;
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x *= scale;
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y *= scale;
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// Depending on which view was selected, rotate around different axes
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switch (active_view)
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{
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case 1:
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rot_x += (int) (y - ypos);
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rot_z += (int) (x - xpos);
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do_redraw = 1;
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break;
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case 3:
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rot_x += (int) (y - ypos);
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rot_y += (int) (x - xpos);
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do_redraw = 1;
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break;
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case 4:
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rot_y += (int) (x - xpos);
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rot_z += (int) (y - ypos);
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do_redraw = 1;
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break;
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default:
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// Do nothing for perspective view, or if no view is selected
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break;
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}
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// Remember cursor position
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xpos = x;
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ypos = y;
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}
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//========================================================================
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// Mouse button callback function
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//========================================================================
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static void mouseButtonFun(GLFWwindow* window, int button, int action, int mods)
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{
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if ((button == GLFW_MOUSE_BUTTON_LEFT) && action == GLFW_PRESS)
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{
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// Detect which of the four views was clicked
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active_view = 1;
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if (xpos >= width / 2)
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active_view += 1;
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if (ypos >= height / 2)
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active_view += 2;
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}
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else if (button == GLFW_MOUSE_BUTTON_LEFT)
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{
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// Deselect any previously selected view
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active_view = 0;
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}
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do_redraw = 1;
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}
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static void key_callback(GLFWwindow* window, int key, int scancode, int action, int mods)
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{
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if (key == GLFW_KEY_ESCAPE && action == GLFW_PRESS)
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glfwSetWindowShouldClose(window, GLFW_TRUE);
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}
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//========================================================================
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// main
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//========================================================================
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int main(void)
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{
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GLFWwindow* window;
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// Initialise GLFW
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if (!glfwInit())
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{
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fprintf(stderr, "Failed to initialize GLFW\n");
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exit(EXIT_FAILURE);
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}
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glfwWindowHint(GLFW_SAMPLES, 4);
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// Open OpenGL window
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window = glfwCreateWindow(500, 500, "Split view demo", NULL, NULL);
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if (!window)
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{
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fprintf(stderr, "Failed to open GLFW window\n");
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glfwTerminate();
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exit(EXIT_FAILURE);
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}
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// Set callback functions
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glfwSetFramebufferSizeCallback(window, framebufferSizeFun);
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glfwSetWindowRefreshCallback(window, windowRefreshFun);
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glfwSetCursorPosCallback(window, cursorPosFun);
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glfwSetMouseButtonCallback(window, mouseButtonFun);
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glfwSetKeyCallback(window, key_callback);
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// Enable vsync
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glfwMakeContextCurrent(window);
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gladLoadGL(glfwGetProcAddress);
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glfwSwapInterval(1);
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if (GLAD_GL_ARB_multisample || GLAD_GL_VERSION_1_3)
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glEnable(GL_MULTISAMPLE_ARB);
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glfwGetFramebufferSize(window, &width, &height);
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framebufferSizeFun(window, width, height);
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// Main loop
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for (;;)
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{
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// Only redraw if we need to
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if (do_redraw)
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windowRefreshFun(window);
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// Wait for new events
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|
glfwWaitEvents();
|
|
|
|
// Check if the window should be closed
|
|
if (glfwWindowShouldClose(window))
|
|
break;
|
|
}
|
|
|
|
// Close OpenGL window and terminate GLFW
|
|
glfwTerminate();
|
|
|
|
exit(EXIT_SUCCESS);
|
|
}
|
|
|
