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73 lines
1.7 KiB
C
73 lines
1.7 KiB
C
/*
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# Depth
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Draw one triangle on top of the other with and without depth.
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Without depth, what gets drawn last wins.
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With depth, more real-world-like rendering happens.
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https://www.youtube.com/watch?v=TbVImw3HJtE
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Still works if triangles overlap, but then generates triangle fragments.
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*/
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#include <stdlib.h>
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#include <GL/gl.h>
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#include <GL/glu.h>
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#include <GL/glut.h>
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int depth = 0;
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static void init() {
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glClearColor(0.0, 0.0, 0.0, 0.0);
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glShadeModel(GL_FLAT);
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if (depth)
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glEnable(GL_DEPTH_TEST);
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}
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static void display(void) {
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if (depth)
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glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
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else
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glClear(GL_COLOR_BUFFER_BIT);
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glLoadIdentity();
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glBegin(GL_TRIANGLES);
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glColor3f(1.0f, 0.0f, 0.0f);
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glVertex3f( 0.0f, 1.0f, 1.0f);
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glVertex3f(-1.0f, -1.0f, 1.0f);
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glVertex3f( 1.0f, -1.0f, 1.0f);
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glColor3f(0.0f, 0.0f, 1.0f);
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glVertex3f(-1.0f, 1.0f, 0.0f);
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glVertex3f( 0.0f, -1.0f, 0.0f);
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glVertex3f( 1.0f, 1.0f, 0.0f);
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glEnd();
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glFlush();
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}
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static void reshape(int w, int h) {
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glViewport(0, 0, w, h);
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glMatrixMode(GL_PROJECTION);
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glLoadIdentity();
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glOrtho(-1.0, 1.0, -1.0, 1.0, -2.0, 1.5);
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glMatrixMode(GL_MODELVIEW);
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}
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int main(int argc, char** argv) {
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glutInit(&argc, argv);
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if (argc > 1)
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depth = 1;
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if (depth)
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glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB | GLUT_DEPTH);
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else
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glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
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glutInitWindowSize(500, 500);
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glutInitWindowPosition(100, 100);
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glutCreateWindow(argv[0]);
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init();
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glutDisplayFunc(display);
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glutReshapeFunc(reshape);
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glutMainLoop();
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return EXIT_SUCCESS;
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}
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