96 lines
2.7 KiB
C
96 lines
2.7 KiB
C
#include "gl.h"
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#include "glu.h"
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#include "glkos.h"
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/* A general OpenGL initialization function. Sets all of the initial parameters. */
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void InitGL(int Width, int Height) // We call this right after our OpenGL window is created.
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{
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glClearColor(0.0f, 0.0f, 0.0f, 0.0f); // This Will Clear The Background Color To Black
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glClearDepth(1.0); // Enables Clearing Of The Depth Buffer
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glDepthFunc(GL_LESS); // The Type Of Depth Test To Do
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glEnable(GL_DEPTH_TEST); // Enables Depth Testing
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glShadeModel(GL_SMOOTH); // Enables Smooth Color Shading
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glMatrixMode(GL_PROJECTION);
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glLoadIdentity(); // Reset The Projection Matrix
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gluPerspective(45.0f,(GLfloat)Width/(GLfloat)Height,0.1f,100.0f); // Calculate The Aspect Ratio Of The Window
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glMatrixMode(GL_MODELVIEW);
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}
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/* The function called when our window is resized (which shouldn't happen, because we're fullscreen) */
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void ReSizeGLScene(int Width, int Height)
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{
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if (Height == 0) // Prevent A Divide By Zero If The Window Is Too Small
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Height = 1;
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glViewport(0, 0, Width, Height); // Reset The Current Viewport And Perspective Transformation
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glMatrixMode(GL_PROJECTION);
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glLoadIdentity();
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gluPerspective(45.0f,(GLfloat)Width/(GLfloat)Height,0.1f,100.0f);
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glMatrixMode(GL_MODELVIEW);
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}
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void DrawSquare(float width, float r, float g, float b, float z) {
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width /= 2;
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glColor3f(r, g, b);
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glBegin(GL_QUADS); // start drawing a polygon (4 sided)
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glVertex3f(-width, width, z); // Top Left
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glVertex3f( width, width, z); // Top Right
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glVertex3f( width,-width, z); // Bottom Right
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glVertex3f(-width,-width, z); // Bottom Left
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glEnd(); // done with the polygon
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}
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/* The main drawing function. */
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void DrawGLScene()
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{
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glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); // Clear The Screen And The Depth Buffer
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glLoadIdentity(); // Reset The View
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glDepthFunc(GL_ALWAYS);
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DrawSquare(100, 1, 1, 1, -5.0f);
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glTranslatef(-2.0, 1.5, 0.0f);
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glDepthFunc(GL_LEQUAL);
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DrawSquare(1.0, 1, 0, 0, -5.0f);
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glTranslatef(1.1, 0, 0);
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glDepthFunc(GL_EQUAL);
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DrawSquare(1.0, 1, 0, 0, -5.0f);
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glTranslatef(1.1, 0, 0);
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glDepthFunc(GL_GEQUAL);
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DrawSquare(1.0, 1, 0, 0, -5.0f);
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glTranslatef(1.1, 0, 0);
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glDepthFunc(GL_LESS);
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DrawSquare(1.0, 1, 0, 0, -4.9f);
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glTranslatef(1.1, 0, 0);
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glDepthFunc(GL_GREATER);
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DrawSquare(1.0, 1, 0, 0, -5.1f);
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// swap buffers to display, since we're double buffered.
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glKosSwapBuffers();
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}
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int main(int argc, char **argv)
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{
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glKosInit();
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InitGL(640, 480);
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ReSizeGLScene(640, 480);
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while(1) {
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DrawGLScene();
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}
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return 0;
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}
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