| /** |
| * Implement glRasterPos + glBitmap with textures + shaders. |
| * Brian Paul |
| * 14 May 2007 |
| */ |
| |
| #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 GLuint FragShader; |
| static GLuint VertShader; |
| static GLuint Program; |
| |
| static GLint Win = 0; |
| static GLint WinWidth = 500, WinHeight = 500; |
| static GLboolean Anim = GL_TRUE; |
| static GLboolean Bitmap = GL_FALSE; |
| static GLfloat Xrot = 20.0f, Yrot = 70.0f; |
| static GLint uTex, uScale; |
| static GLuint Textures[2]; |
| |
| #define TEX_WIDTH 16 |
| #define TEX_HEIGHT 8 |
| |
| |
| static void |
| BitmapText(const char *s) |
| { |
| while (*s) { |
| glutBitmapCharacter(GLUT_BITMAP_8_BY_13, (int) *s); |
| s++; |
| } |
| } |
| |
| |
| static void |
| Redisplay(void) |
| { |
| static const GLfloat px[3] = { 1.2, 0, 0}; |
| static const GLfloat nx[3] = {-1.2, 0, 0}; |
| |
| glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); |
| |
| glPushMatrix(); |
| glRotatef(Xrot, 1.0f, 0.0f, 0.0f); |
| glRotatef(Yrot, 0.0f, 1.0f, 0.0f); |
| |
| glEnable(GL_LIGHTING); |
| |
| glPushMatrix(); |
| glScalef(0.5, 0.5, 0.5); |
| glutSolidDodecahedron(); |
| glPopMatrix(); |
| |
| glDisable(GL_LIGHTING); |
| |
| glColor3f(0, 1, 0); |
| glBegin(GL_LINES); |
| glVertex3f(-1, 0, 0); |
| glVertex3f( 1, 0, 0); |
| glEnd(); |
| |
| glColor3f(1, 1, 0); |
| |
| if (Bitmap) { |
| glRasterPos3fv(px); |
| BitmapText("+X"); |
| glRasterPos3fv(nx); |
| BitmapText("-X"); |
| } |
| else { |
| glUseProgram(Program); |
| |
| /* vertex positions (deltas) depend on texture size and window size */ |
| if (uScale != -1) { |
| glUniform2f(uScale, |
| 2.0 * TEX_WIDTH / WinWidth, |
| 2.0 * TEX_HEIGHT / WinHeight); |
| } |
| |
| /* draw +X */ |
| glBindTexture(GL_TEXTURE_2D, Textures[0]); |
| glBegin(GL_QUADS); |
| glTexCoord2f(0, 0); glVertex3fv(px); |
| glTexCoord2f(1, 0); glVertex3fv(px); |
| glTexCoord2f(1, 1); glVertex3fv(px); |
| glTexCoord2f(0, 1); glVertex3fv(px); |
| glEnd(); |
| |
| /* draw -X */ |
| glBindTexture(GL_TEXTURE_2D, Textures[1]); |
| glBegin(GL_QUADS); |
| glTexCoord2f(0, 0); glVertex3fv(nx); |
| glTexCoord2f(1, 0); glVertex3fv(nx); |
| glTexCoord2f(1, 1); glVertex3fv(nx); |
| glTexCoord2f(0, 1); glVertex3fv(nx); |
| glEnd(); |
| |
| glUseProgram(0); |
| } |
| |
| glPopMatrix(); |
| |
| glutSwapBuffers(); |
| } |
| |
| |
| static void |
| Idle(void) |
| { |
| Yrot = glutGet(GLUT_ELAPSED_TIME) * 0.01; |
| glutPostRedisplay(); |
| } |
| |
| |
| static void |
| Reshape(int width, int height) |
| { |
| WinWidth = width; |
| WinHeight = height; |
| glViewport(0, 0, width, height); |
| glMatrixMode(GL_PROJECTION); |
| glLoadIdentity(); |
| glFrustum(-1.0, 1.0, -1.0, 1.0, 5.0, 25.0); |
| glMatrixMode(GL_MODELVIEW); |
| glLoadIdentity(); |
| glTranslatef(0.0f, 0.0f, -10.0f); |
| } |
| |
| |
| static void |
| Key(unsigned char key, int x, int y) |
| { |
| (void) x; |
| (void) y; |
| |
| switch(key) { |
| case ' ': |
| case 'a': |
| Anim = !Anim; |
| if (Anim) |
| glutIdleFunc(Idle); |
| else |
| glutIdleFunc(NULL); |
| break; |
| case 'b': |
| Bitmap = !Bitmap; |
| if (Bitmap) |
| printf("Using glBitmap\n"); |
| else |
| printf("Using billboard texture\n"); |
| break; |
| case 27: |
| glDeleteShader(FragShader); |
| glDeleteShader(VertShader); |
| glDeleteProgram(Program); |
| glutDestroyWindow(Win); |
| exit(0); |
| } |
| glutPostRedisplay(); |
| } |
| |
| |
| static void |
| SpecialKey(int key, int x, int y) |
| { |
| const GLfloat step = 0.125f; |
| switch(key) { |
| case GLUT_KEY_UP: |
| Xrot -= step; |
| break; |
| case GLUT_KEY_DOWN: |
| Xrot += step; |
| break; |
| case GLUT_KEY_LEFT: |
| Yrot -= step; |
| break; |
| case GLUT_KEY_RIGHT: |
| Yrot += step; |
| break; |
| } |
| /*printf("Xrot: %f Yrot: %f\n", Xrot, Yrot);*/ |
| glutPostRedisplay(); |
| } |
| |
| |
| static void |
| MakeTexImage(const char *p, GLuint texobj) |
| { |
| GLubyte image[TEX_HEIGHT][TEX_WIDTH]; |
| GLuint i, j, k; |
| |
| for (i = 0; i < TEX_HEIGHT; i++) { |
| for (j = 0; j < TEX_WIDTH; j++) { |
| k = i * TEX_WIDTH + j; |
| if (p[k] == ' ') { |
| image[i][j] = 0; |
| } |
| else { |
| image[i][j] = 255; |
| } |
| } |
| } |
| |
| glBindTexture(GL_TEXTURE_2D, texobj); |
| glTexImage2D(GL_TEXTURE_2D, 0, GL_INTENSITY, TEX_WIDTH, TEX_HEIGHT, 0, |
| GL_RED, GL_UNSIGNED_BYTE, image); |
| glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAX_LEVEL, 1); |
| glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST); |
| glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST); |
| } |
| |
| |
| static void |
| MakeBitmapTextures(void) |
| { |
| const char *px = |
| " X X " |
| " X X X " |
| " X X X " |
| " XXXXX X " |
| " X X X " |
| " X X X " |
| " X X " |
| " X X "; |
| const char *nx = |
| " X X " |
| " X X " |
| " X X " |
| " XXXXX X " |
| " X X " |
| " X X " |
| " X X " |
| " X X "; |
| glGenTextures(2, Textures); |
| MakeTexImage(px, Textures[0]); |
| MakeTexImage(nx, Textures[1]); |
| } |
| |
| |
| static void |
| Init(void) |
| { |
| /* Fragment shader: modulate raster color by texture, discard fragments |
| * with alpha < 1.0 |
| */ |
| static const char *fragShaderText = |
| "uniform sampler2D tex2d; \n" |
| "void main() {\n" |
| " vec4 c = texture2D(tex2d, gl_TexCoord[0].xy); \n" |
| " if (c.w < 1.0) \n" |
| " discard; \n" |
| " gl_FragColor = c * gl_Color; \n" |
| "}\n"; |
| /* Vertex shader: compute new vertex position based on incoming vertex pos, |
| * texcoords and special scale factor. |
| */ |
| static const char *vertShaderText = |
| "uniform vec2 scale; \n" |
| "void main() {\n" |
| " vec4 p = gl_ModelViewProjectionMatrix * gl_Vertex;\n" |
| " gl_Position.xy = p.xy + gl_MultiTexCoord0.xy * scale * p.w; \n" |
| " gl_Position.zw = p.zw; \n" |
| " gl_TexCoord[0] = gl_MultiTexCoord0; \n" |
| " gl_FrontColor = gl_Color; \n" |
| "}\n"; |
| |
| if (!ShadersSupported()) |
| exit(1); |
| |
| VertShader = CompileShaderText(GL_VERTEX_SHADER, vertShaderText); |
| FragShader = CompileShaderText(GL_FRAGMENT_SHADER, fragShaderText); |
| Program = LinkShaders(VertShader, FragShader); |
| |
| glUseProgram(Program); |
| |
| uScale = glGetUniformLocation(Program, "scale"); |
| uTex = glGetUniformLocation(Program, "tex2d"); |
| if (uTex != -1) { |
| glUniform1i(uTex, 0); /* tex unit 0 */ |
| } |
| |
| glUseProgram(0); |
| |
| glClearColor(0.3f, 0.3f, 0.3f, 0.0f); |
| glEnable(GL_DEPTH_TEST); |
| glEnable(GL_NORMALIZE); |
| glEnable(GL_LIGHT0); |
| |
| MakeBitmapTextures(); |
| } |
| |
| |
| int |
| main(int argc, char *argv[]) |
| { |
| glutInit(&argc, argv); |
| glutInitWindowSize(WinWidth, WinHeight); |
| glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH); |
| Win = glutCreateWindow(argv[0]); |
| glewInit(); |
| glutReshapeFunc(Reshape); |
| glutKeyboardFunc(Key); |
| glutSpecialFunc(SpecialKey); |
| glutDisplayFunc(Redisplay); |
| if (Anim) |
| glutIdleFunc(Idle); |
| Init(); |
| glutMainLoop(); |
| return 0; |
| } |
| |
| |