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- /**
- * Draw two quads, one using only a vertex shader, the other only with a
- * fragment shader. They should appear the same.
- * 17 Dec 2008
- * Brian Paul
- */
-
-
- #include <assert.h>
- #include <string.h>
- #include <stdio.h>
- #include <stdlib.h>
- #include <math.h>
- #include <GL/glew.h>
- #include <GL/glut.h>
- #include "shaderutil.h"
-
-
- static char *FragProgFile = NULL;
- static char *VertProgFile = NULL;
- static GLuint FragShader;
- static GLuint VertShader;
- static GLuint VertProgram; /* w/out vertex shader */
- static GLuint FragProgram; /* w/out fragment shader */
- static GLint Win = 0;
-
-
- static void
- DrawQuadColor(void)
- {
- glBegin(GL_QUADS);
- glColor3f(1, 0, 0); glVertex2f(-1, -1);
- glColor3f(0, 1, 0); glVertex2f( 1, -1);
- glColor3f(0, 0, 1); glVertex2f( 1, 1);
- glColor3f(1, 0, 1); glVertex2f(-1, 1);
- glEnd();
- }
-
-
- /** as above, but specify color via texcoords */
- static void
- DrawQuadTex(void)
- {
- glBegin(GL_QUADS);
- glTexCoord3f(1, 0, 0); glVertex2f(-1, -1);
- glTexCoord3f(0, 1, 0); glVertex2f( 1, -1);
- glTexCoord3f(0, 0, 1); glVertex2f( 1, 1);
- glTexCoord3f(1, 0, 1); glVertex2f(-1, 1);
- glEnd();
- }
-
-
- static void
- Redisplay(void)
- {
- glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
-
- /* render with vertex shader only */
- glUseProgram(VertProgram);
- glPushMatrix();
- glTranslatef(-1.5, 0, 0);
- DrawQuadTex();
- glPopMatrix();
-
- /* render with fragment shader only */
- glUseProgram(FragProgram);
- glPushMatrix();
- glTranslatef(+1.5, 0, 0);
- DrawQuadColor();
- glPopMatrix();
-
- glutSwapBuffers();
- }
-
-
- static void
- Reshape(int width, int height)
- {
- glViewport(0, 0, width, height);
- glMatrixMode(GL_PROJECTION);
- glLoadIdentity();
- glOrtho(-4, 4, -2, 2, -1, 1);
- glMatrixMode(GL_MODELVIEW);
- glLoadIdentity();
- }
-
-
- static void
- CleanUp(void)
- {
- glDeleteShader(FragShader);
- glDeleteShader(VertShader);
- glDeleteProgram(VertProgram);
- glDeleteProgram(FragProgram);
- glutDestroyWindow(Win);
- }
-
-
- static void
- Key(unsigned char key, int x, int y)
- {
- (void) x;
- (void) y;
- switch(key) {
- case 27:
- CleanUp();
- exit(0);
- break;
- }
- glutPostRedisplay();
- }
-
-
- static void
- Init(void)
- {
- static const char *fragShaderText =
- "void main() {\n"
- " gl_FragColor = gl_Color;\n"
- "}\n";
- static const char *vertShaderText =
- "void main() {\n"
- " gl_Position = ftransform();\n"
- " gl_FrontColor = gl_MultiTexCoord0;\n" /* see DrawQuadTex() */
- "}\n";
-
- if (!ShadersSupported())
- exit(1);
-
- if (FragProgFile)
- FragShader = CompileShaderFile(GL_FRAGMENT_SHADER, FragProgFile);
- else
- FragShader = CompileShaderText(GL_FRAGMENT_SHADER, fragShaderText);
-
- if (VertProgFile)
- VertShader = CompileShaderFile(GL_VERTEX_SHADER, VertProgFile);
- else
- VertShader = CompileShaderText(GL_VERTEX_SHADER, vertShaderText);
-
- VertProgram = LinkShaders(VertShader, 0);
- FragProgram = LinkShaders(0, FragShader);
-
- glClearColor(0.3f, 0.3f, 0.3f, 0.0f);
- glEnable(GL_DEPTH_TEST);
-
- printf("GL_RENDERER = %s\n",(const char *) glGetString(GL_RENDERER));
-
- assert(glIsProgram(VertProgram));
- assert(glIsProgram(FragProgram));
- assert(glIsShader(FragShader));
- assert(glIsShader(VertShader));
-
- glColor3f(1, 0, 0);
- }
-
-
- static void
- ParseOptions(int argc, char *argv[])
- {
- int i;
- for (i = 1; i < argc; i++) {
- if (strcmp(argv[i], "-fs") == 0) {
- FragProgFile = argv[i+1];
- }
- else if (strcmp(argv[i], "-vs") == 0) {
- VertProgFile = argv[i+1];
- }
- }
- }
-
-
- int
- main(int argc, char *argv[])
- {
- glutInit(&argc, argv);
- glutInitWindowSize(400, 200);
- glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH);
- Win = glutCreateWindow(argv[0]);
- glewInit();
- glutReshapeFunc(Reshape);
- glutKeyboardFunc(Key);
- glutDisplayFunc(Redisplay);
- ParseOptions(argc, argv);
- Init();
- glutMainLoop();
- return 0;
- }
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