diff options
Diffstat (limited to 'progs/vpglsl/vp-tris.c')
| -rw-r--r-- | progs/vpglsl/vp-tris.c | 265 |
1 files changed, 265 insertions, 0 deletions
diff --git a/progs/vpglsl/vp-tris.c b/progs/vpglsl/vp-tris.c new file mode 100644 index 0000000000..1d1b639b56 --- /dev/null +++ b/progs/vpglsl/vp-tris.c @@ -0,0 +1,265 @@ + +#include <assert.h> +#include <string.h> +#include <stdio.h> +#include <stdlib.h> +#include <math.h> +#define GL_GLEXT_PROTOTYPES +#include <GL/glut.h> + +static const char *filename = NULL; +static GLuint nr_steps = 4; + +static GLuint fragShader; +static GLuint vertShader; +static GLuint program; + +static void usage( char *name ) +{ + fprintf( stderr, "usage: %s [ options ] shader_filename\n", name ); + fprintf( stderr, "\n" ); + fprintf( stderr, "options:\n" ); + fprintf( stderr, " -f flat shaded\n" ); + fprintf( stderr, " -nNr subdivision steps\n" ); +} + + +static void load_and_compile_shader(GLuint shader, const char *text) +{ + GLint stat; + + glShaderSource(shader, 1, (const GLchar **) &text, NULL); + + glCompileShader(shader); + + glGetShaderiv(shader, GL_COMPILE_STATUS, &stat); + if (!stat) { + GLchar log[1000]; + GLsizei len; + glGetShaderInfoLog(shader, 1000, &len, log); + fprintf(stderr, "vp-tris: problem compiling shader:\n%s\n", log); + exit(1); + } +} + +static void read_shader(GLuint shader, const char *filename) +{ + const int max = 100*1000; + int n; + char *buffer = (char*) malloc(max); + FILE *f = fopen(filename, "r"); + if (!f) { + fprintf(stderr, "vp-tris: Unable to open shader file %s\n", filename); + exit(1); + } + + n = fread(buffer, 1, max, f); + printf("fslight: read %d bytes from shader file %s\n", n, filename); + if (n > 0) { + buffer[n] = 0; + load_and_compile_shader(shader, buffer); + } + + fclose(f); + free(buffer); +} + +static void check_link(GLuint prog) +{ + GLint stat; + glGetProgramiv(prog, GL_LINK_STATUS, &stat); + if (!stat) { + GLchar log[1000]; + GLsizei len; + glGetProgramInfoLog(prog, 1000, &len, log); + fprintf(stderr, "Linker error:\n%s\n", log); + } +} + +static void prepare_shaders() +{ + static const char *fragShaderText = + "void main() {\n" + " gl_FragColor = gl_Color;\n" + "}\n"; + static const char *vertShaderText = + "void main() {\n" + " gl_FrontColor = gl_Color;\n" + " gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;\n" + "}\n"; + fragShader = glCreateShader(GL_FRAGMENT_SHADER); + load_and_compile_shader(fragShader, fragShaderText); + + + vertShader = glCreateShader(GL_VERTEX_SHADER); + if (filename) + read_shader(vertShader, filename); + else + load_and_compile_shader(vertShader, vertShaderText); + + program = glCreateProgram(); + glAttachShader(program, fragShader); + glAttachShader(program, vertShader); + glLinkProgram(program); + check_link(program); + glUseProgram(program); +} + +static void args(int argc, char *argv[]) +{ + GLint i; + + for (i = 1; i < argc; i++) { + if (strncmp(argv[i], "-n", 2) == 0) { + nr_steps = atoi((argv[i]) + 2); + } + else if (strcmp(argv[i], "-f") == 0) { + glShadeModel(GL_FLAT); + } + else if (i == argc - 1) { + filename = argv[i]; + } + else { + usage(argv[0]); + exit(1); + } + } + + if (!filename) { + usage(argv[0]); + exit(1); + } +} + + + + +union vert { + struct { + GLfloat color[3]; + GLfloat pos[3]; + } v; + GLfloat f[6]; +}; + +static void make_midpoint( union vert *out, + const union vert *v0, + const union vert *v1) +{ + int i; + for (i = 0; i < 6; i++) + out->f[i] = v0->f[i] + .5 * (v1->f[i] - v0->f[i]); +} + +static void subdiv( union vert *v0, + union vert *v1, + union vert *v2, + GLuint depth ) +{ + if (depth == 0) { + glColor3fv(v0->v.color); + glVertex3fv(v0->v.pos); + glColor3fv(v1->v.color); + glVertex3fv(v1->v.pos); + glColor3fv(v2->v.color); + glVertex3fv(v2->v.pos); + } + else { + union vert m[3]; + + make_midpoint(&m[0], v0, v1); + make_midpoint(&m[1], v1, v2); + make_midpoint(&m[2], v2, v0); + + subdiv(&m[0], &m[2], v0, depth-1); + subdiv(&m[1], &m[0], v1, depth-1); + subdiv(&m[2], &m[1], v2, depth-1); + subdiv(&m[0], &m[1], &m[2], depth-1); + } +} + +/** Assignment */ +#define ASSIGN_3V( V, V0, V1, V2 ) \ +do { \ + V[0] = V0; \ + V[1] = V1; \ + V[2] = V2; \ +} while(0) + +static void Display( void ) +{ + glClearColor(0.3, 0.3, 0.3, 1); + glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT ); + + glUseProgram(program); + + glBegin(GL_TRIANGLES); + + + { + union vert v[3]; + + ASSIGN_3V(v[0].v.color, 0,0,1); + ASSIGN_3V(v[0].v.pos, 0.9, -0.9, 0.0); + ASSIGN_3V(v[1].v.color, 1,0,0); + ASSIGN_3V(v[1].v.pos, 0.9, 0.9, 0.0); + ASSIGN_3V(v[2].v.color, 0,1,0); + ASSIGN_3V(v[2].v.pos, -0.9, 0, 0.0); + + subdiv(&v[0], &v[1], &v[2], nr_steps); + } + + glEnd(); + + + glFlush(); +} + + +static void Reshape( int width, int height ) +{ + glViewport( 0, 0, width, height ); + glMatrixMode( GL_PROJECTION ); + glLoadIdentity(); + glOrtho(-1.0, 1.0, -1.0, 1.0, -0.5, 1000.0); + glMatrixMode( GL_MODELVIEW ); + glLoadIdentity(); + /*glTranslatef( 0.0, 0.0, -15.0 );*/ +} + + +static void CleanUp(void) +{ + glDeleteShader(fragShader); + glDeleteShader(vertShader); + glDeleteProgram(program); +} + +static void Key( unsigned char key, int x, int y ) +{ + (void) x; + (void) y; + switch (key) { + case 27: + CleanUp(); + exit(0); + break; + } + glutPostRedisplay(); +} + +int main( int argc, char *argv[] ) +{ + glutInit( &argc, argv ); + glutInitWindowPosition( 0, 0 ); + glutInitWindowSize( 250, 250 ); + glutInitDisplayMode( GLUT_RGB | GLUT_SINGLE | GLUT_DEPTH ); + glutCreateWindow(argv[0]); + glutReshapeFunc( Reshape ); + glutKeyboardFunc( Key ); + glutDisplayFunc( Display ); + args( argc, argv ); + prepare_shaders(); + glutMainLoop(); + return 0; +} |