diff options
Diffstat (limited to 'progs/glsl/twoside.c')
| -rw-r--r-- | progs/glsl/twoside.c | 294 |
1 files changed, 294 insertions, 0 deletions
diff --git a/progs/glsl/twoside.c b/progs/glsl/twoside.c new file mode 100644 index 00000000000..672a00491e6 --- /dev/null +++ b/progs/glsl/twoside.c @@ -0,0 +1,294 @@ +/** + * Test two-sided lighting with shaders. + * Both GL_VERTEX_PROGRAM_TWO_SIDE and gl_FrontFacing can be tested + * (see keys below). + * + * Brian Paul + * 18 Dec 2007 + */ + +#include <assert.h> +#include <string.h> +#include <stdio.h> +#include <stdlib.h> +#include <math.h> +#include <GL/gl.h> +#include <GL/glut.h> +#include <GL/glext.h> +#include "extfuncs.h" +#include "shaderutil.h" + + +static GLint WinWidth = 300, WinHeight = 300; +static char *FragProgFile = NULL; +static char *VertProgFile = NULL; +static GLuint fragShader; +static GLuint vertShader; +static GLuint program; +static GLint win = 0; +static GLboolean anim = 0*GL_TRUE; +static GLboolean DetermineInFragProg = GL_TRUE; +static GLfloat Xrot = 30.0f; +static GLint u_fragface; +static GLenum FrontWinding = GL_CCW; +static int prevTime = 0; + + +static const GLfloat Red[4] = {1, 0, 0, 0}; +static const GLfloat Green[4] = {0, 1, 0, 0}; + + +static void +Redisplay(void) +{ + int i; + float radius = 2; + + glFrontFace(FrontWinding); + + if (DetermineInFragProg) { + glUniform1i_func(u_fragface, 1); + glDisable(GL_VERTEX_PROGRAM_TWO_SIDE); + } + else { + glUniform1i_func(u_fragface, 0); + glEnable(GL_VERTEX_PROGRAM_TWO_SIDE); + } + + glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT ); + + glPushMatrix(); + glRotatef(Xrot, 1, 0, 0); + + /* Draw a tristrip ring */ + glBegin(GL_TRIANGLE_STRIP); + glColor4fv(Red); + glSecondaryColor3fv_func(Green); + for (i = 0; i < 20; i++) { + float a = i / 19.0 * M_PI * 2.0; + float x = radius * cos(a); + float y = radius * sin(a); + glVertex3f(x, -1, y); + glVertex3f(x, +1, y); + } + glEnd(); + + glPopMatrix(); + + glutSwapBuffers(); +} + + +static void +Idle(void) +{ + int curTime = glutGet(GLUT_ELAPSED_TIME); + int dt = curTime - prevTime; + + if (prevTime == 0) { + prevTime = curTime; + return; + } + prevTime = curTime; + + Xrot += dt * 0.1; + glutPostRedisplay(); +} + + +static void +Reshape(int width, int height) +{ + float ar = (float) width / height; + glViewport(0, 0, width, height); + glMatrixMode(GL_PROJECTION); + glLoadIdentity(); + glFrustum(-ar, ar, -1, 1, 3, 25); + glMatrixMode(GL_MODELVIEW); + glLoadIdentity(); + glTranslatef(0, 0, -10); +} + + +static void +CleanUp(void) +{ + glDeleteShader_func(fragShader); + glDeleteShader_func(vertShader); + glDeleteProgram_func(program); + glutDestroyWindow(win); +} + + +static void +Key(unsigned char key, int x, int y) +{ + (void) x; + (void) y; + + switch(key) { + case ' ': + case 'a': + anim = !anim; + if (anim) { + prevTime = glutGet(GLUT_ELAPSED_TIME); + glutIdleFunc(Idle); + } + else + glutIdleFunc(NULL); + break; + case 'f': + printf("Using frag shader gl_FrontFacing\n"); + DetermineInFragProg = GL_TRUE; + break; + case 'v': + printf("Using vert shader Two-sided lighting\n"); + DetermineInFragProg = GL_FALSE; + break; + case 'r': + /* reset */ + Xrot = 30; + anim = 0; + glutIdleFunc(NULL); + break; + case 's': + Xrot += 5; + break; + case 'S': + Xrot -= 5; + break; + case 'w': + if (FrontWinding == GL_CCW) { + FrontWinding = GL_CW; + printf("FrontFace = GL_CW\n"); + } + else { + FrontWinding = GL_CCW; + printf("FrontFace = GL_CCW\n"); + } + break; + case 27: + CleanUp(); + exit(0); + break; + } + glutPostRedisplay(); +} + + +static void +Init(void) +{ + static const char *fragShaderText = + "uniform bool fragface; \n" + "void main() { \n" +#if 0 + " if (!fragface || gl_FrontFacing) { \n" + " gl_FragColor = gl_Color; \n" + " } \n" + " else { \n" + " gl_FragColor = 0.8 * gl_SecondaryColor; \n" + " } \n" +#else + " bool f = gl_FrontFacing; \n" + " if (f) { \n" + " gl_FragColor = vec4(1.0, 0.0, 0.0, 0.0); \n" + " } \n" + " else { \n" + " gl_FragColor = vec4(0.0, 1.0, 0.0, 0.0); \n" + " } \n" + " //float g = float(gl_FrontFacing) * 0.5 + 0.5; \n" + " //gl_FragColor = vec4(g); \n" +#endif + "} \n"; + static const char *vertShaderText = + "uniform bool fragface; \n" + "void main() { \n" + " gl_FrontColor = gl_Color; \n" + " if (fragface) { \n" + " // front/back chosen in frag prog \n" + " gl_FrontSecondaryColor = gl_SecondaryColor; \n" + " } \n" + " else { \n" + " // front/back chosen in prim setup \n" + " gl_BackColor = gl_SecondaryColor; \n" + " } \n" + " gl_Position = ftransform(); \n" + "} \n"; + + if (!ShadersSupported()) + exit(1); + + GetExtensionFuncs(); + + vertShader = CompileShaderText(GL_VERTEX_SHADER, vertShaderText); + fragShader = CompileShaderText(GL_FRAGMENT_SHADER, fragShaderText); + program = LinkShaders(vertShader, fragShader); + + glUseProgram_func(program); + + u_fragface = glGetUniformLocation_func(program, "fragface"); + printf("Uniforms: %d\n", u_fragface); + + /*assert(glGetError() == 0);*/ + + glClearColor(0.3f, 0.3f, 0.3f, 0.0f); + + printf("GL_RENDERER = %s\n",(const char *) glGetString(GL_RENDERER)); + + assert(glIsProgram_func(program)); + assert(glIsShader_func(fragShader)); + assert(glIsShader_func(vertShader)); + + glEnable(GL_DEPTH_TEST); +} + + +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]; + } + } +} + + +static void +Usage(void) +{ + printf("Keys:\n"); + printf(" f - do front/back determination in fragment shader\n"); + printf(" v - do front/back determination in vertex shader\n"); + printf(" r - reset, show front\n"); + printf(" a - toggle animation\n"); + printf(" s - step rotation\n"); + printf(" w - toggle CW, CCW front-face winding\n"); + printf("NOTE: red = front face, green = back face.\n"); +} + + +int +main(int argc, char *argv[]) +{ + glutInit(&argc, argv); + glutInitWindowPosition( 0, 0); + glutInitWindowSize(WinWidth, WinHeight); + glutInitDisplayMode(GLUT_RGB | GLUT_DEPTH | GLUT_DOUBLE); + win = glutCreateWindow(argv[0]); + glutReshapeFunc(Reshape); + glutKeyboardFunc(Key); + glutDisplayFunc(Redisplay); + if (anim) + glutIdleFunc(Idle); + ParseOptions(argc, argv); + Init(); + Usage(); + glutMainLoop(); + return 0; +} |