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| 1 // | |
| 2 // Book: OpenGL(R) ES 2.0 Programming Guide | |
| 3 // Authors: Aaftab Munshi, Dan Ginsburg, Dave Shreiner | |
| 4 // ISBN-10: 0321502795 | |
| 5 // ISBN-13: 9780321502797 | |
| 6 // Publisher: Addison-Wesley Professional | |
| 7 // URLs: http://safari.informit.com/9780321563835 | |
| 8 // http://www.opengles-book.com | |
| 9 // | |
| 10 | |
| 11 // MipMap2D.c | |
| 12 // | |
| 13 // This is a simple example that demonstrates generating a mipmap chain | |
| 14 // and rendering with it | |
| 15 // | |
| 16 #include <stdlib.h> | |
| 17 #include "esUtil.h" | |
| 18 | |
| 19 typedef struct | |
| 20 { | |
| 21 // Handle to a program object | |
| 22 GLuint programObject; | |
| 23 | |
| 24 // Attribute locations | |
| 25 GLint positionLoc; | |
| 26 GLint texCoordLoc; | |
| 27 | |
| 28 // Sampler location | |
| 29 GLint samplerLoc; | |
| 30 | |
| 31 // Offset location | |
| 32 GLint offsetLoc; | |
| 33 | |
| 34 // Texture handle | |
| 35 GLuint textureId; | |
| 36 | |
| 37 } UserData; | |
| 38 | |
| 39 | |
| 40 /// | |
| 41 // From an RGB8 source image, generate the next level mipmap | |
| 42 // | |
| 43 GLboolean GenMipMap2D( GLubyte *src, GLubyte **dst, int srcWidth, int srcHeight,
int *dstWidth, int *dstHeight ) | |
| 44 { | |
| 45 int x, | |
| 46 y; | |
| 47 int texelSize = 3; | |
| 48 | |
| 49 *dstWidth = srcWidth / 2; | |
| 50 if ( *dstWidth <= 0 ) | |
| 51 *dstWidth = 1; | |
| 52 | |
| 53 *dstHeight = srcHeight / 2; | |
| 54 if ( *dstHeight <= 0 ) | |
| 55 *dstHeight = 1; | |
| 56 | |
| 57 *dst = malloc ( sizeof(GLubyte) * texelSize * (*dstWidth) * (*dstHeight) ); | |
| 58 if ( *dst == NULL ) | |
| 59 return GL_FALSE; | |
| 60 | |
| 61 for ( y = 0; y < *dstHeight; y++ ) | |
| 62 { | |
| 63 for( x = 0; x < *dstWidth; x++ ) | |
| 64 { | |
| 65 int srcIndex[4]; | |
| 66 float r = 0.0f, | |
| 67 g = 0.0f, | |
| 68 b = 0.0f; | |
| 69 int sample; | |
| 70 | |
| 71 // Compute the offsets for 2x2 grid of pixels in previous | |
| 72 // image to perform box filter | |
| 73 srcIndex[0] = | |
| 74 (((y * 2) * srcWidth) + (x * 2)) * texelSize; | |
| 75 srcIndex[1] = | |
| 76 (((y * 2) * srcWidth) + (x * 2 + 1)) * texelSize; | |
| 77 srcIndex[2] = | |
| 78 ((((y * 2) + 1) * srcWidth) + (x * 2)) * texelSize; | |
| 79 srcIndex[3] = | |
| 80 ((((y * 2) + 1) * srcWidth) + (x * 2 + 1)) * texelSize; | |
| 81 | |
| 82 // Sum all pixels | |
| 83 for ( sample = 0; sample < 4; sample++ ) | |
| 84 { | |
| 85 r += src[srcIndex[sample]]; | |
| 86 g += src[srcIndex[sample] + 1]; | |
| 87 b += src[srcIndex[sample] + 2]; | |
| 88 } | |
| 89 | |
| 90 // Average results | |
| 91 r /= 4.0; | |
| 92 g /= 4.0; | |
| 93 b /= 4.0; | |
| 94 | |
| 95 // Store resulting pixels | |
| 96 (*dst)[ ( y * (*dstWidth) + x ) * texelSize ] = (GLubyte)( r ); | |
| 97 (*dst)[ ( y * (*dstWidth) + x ) * texelSize + 1] = (GLubyte)( g ); | |
| 98 (*dst)[ ( y * (*dstWidth) + x ) * texelSize + 2] = (GLubyte)( b ); | |
| 99 } | |
| 100 } | |
| 101 | |
| 102 return GL_TRUE; | |
| 103 } | |
| 104 | |
| 105 /// | |
| 106 // Generate an RGB8 checkerboard image | |
| 107 // | |
| 108 GLubyte* GenCheckImage( int width, int height, int checkSize ) | |
| 109 { | |
| 110 int x, | |
| 111 y; | |
| 112 GLubyte *pixels = malloc( width * height * 3 ); | |
| 113 | |
| 114 if ( pixels == NULL ) | |
| 115 return NULL; | |
| 116 | |
| 117 for ( y = 0; y < height; y++ ) | |
| 118 for ( x = 0; x < width; x++ ) | |
| 119 { | |
| 120 GLubyte rColor = 0; | |
| 121 GLubyte bColor = 0; | |
| 122 | |
| 123 if ( ( x / checkSize ) % 2 == 0 ) | |
| 124 { | |
| 125 rColor = 255 * ( ( y / checkSize ) % 2 ); | |
| 126 bColor = 255 * ( 1 - ( ( y / checkSize ) % 2 ) ); | |
| 127 } | |
| 128 else | |
| 129 { | |
| 130 bColor = 255 * ( ( y / checkSize ) % 2 ); | |
| 131 rColor = 255 * ( 1 - ( ( y / checkSize ) % 2 ) ); | |
| 132 } | |
| 133 | |
| 134 pixels[(y * height + x) * 3] = rColor; | |
| 135 pixels[(y * height + x) * 3 + 1] = 0; | |
| 136 pixels[(y * height + x) * 3 + 2] = bColor; | |
| 137 } | |
| 138 | |
| 139 return pixels; | |
| 140 } | |
| 141 | |
| 142 /// | |
| 143 // Create a mipmapped 2D texture image | |
| 144 // | |
| 145 GLuint CreateMipMappedTexture2D( ) | |
| 146 { | |
| 147 // Texture object handle | |
| 148 GLuint textureId; | |
| 149 int width = 256, | |
| 150 height = 256; | |
| 151 int level; | |
| 152 GLubyte *pixels; | |
| 153 GLubyte *prevImage; | |
| 154 GLubyte *newImage; | |
| 155 | |
| 156 pixels = GenCheckImage( width, height, 8 ); | |
| 157 if ( pixels == NULL ) | |
| 158 return 0; | |
| 159 | |
| 160 // Generate a texture object | |
| 161 glGenTextures ( 1, &textureId ); | |
| 162 | |
| 163 // Bind the texture object | |
| 164 glBindTexture ( GL_TEXTURE_2D, textureId ); | |
| 165 | |
| 166 // Load mipmap level 0 | |
| 167 glTexImage2D ( GL_TEXTURE_2D, 0, GL_RGB, width, height, | |
| 168 0, GL_RGB, GL_UNSIGNED_BYTE, pixels ); | |
| 169 | |
| 170 level = 1; | |
| 171 prevImage = &pixels[0]; | |
| 172 | |
| 173 while ( width > 1 && height > 1 ) | |
| 174 { | |
| 175 int newWidth, | |
| 176 newHeight; | |
| 177 | |
| 178 // Generate the next mipmap level | |
| 179 GenMipMap2D( prevImage, &newImage, width, height, | |
| 180 &newWidth, &newHeight ); | |
| 181 | |
| 182 // Load the mipmap level | |
| 183 glTexImage2D( GL_TEXTURE_2D, level, GL_RGB, | |
| 184 newWidth, newHeight, 0, GL_RGB, | |
| 185 GL_UNSIGNED_BYTE, newImage ); | |
| 186 | |
| 187 // Free the previous image | |
| 188 free ( prevImage ); | |
| 189 | |
| 190 // Set the previous image for the next iteration | |
| 191 prevImage = newImage; | |
| 192 level++; | |
| 193 | |
| 194 // Half the width and height | |
| 195 width = newWidth; | |
| 196 height = newHeight; | |
| 197 } | |
| 198 | |
| 199 free ( newImage ); | |
| 200 | |
| 201 // Set the filtering mode | |
| 202 glTexParameteri ( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST_MIPMAP_NEA
REST ); | |
| 203 glTexParameteri ( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR ); | |
| 204 | |
| 205 return textureId; | |
| 206 | |
| 207 } | |
| 208 | |
| 209 | |
| 210 /// | |
| 211 // Initialize the shader and program object | |
| 212 // | |
| 213 int Init ( ESContext *esContext ) | |
| 214 { | |
| 215 UserData *userData = esContext->userData; | |
| 216 GLbyte vShaderStr[] = | |
| 217 "uniform float u_offset; \n" | |
| 218 "attribute vec4 a_position; \n" | |
| 219 "attribute vec2 a_texCoord; \n" | |
| 220 "varying vec2 v_texCoord; \n" | |
| 221 "void main() \n" | |
| 222 "{ \n" | |
| 223 " gl_Position = a_position; \n" | |
| 224 " gl_Position.x += u_offset;\n" | |
| 225 " v_texCoord = a_texCoord; \n" | |
| 226 "} \n"; | |
| 227 | |
| 228 GLbyte fShaderStr[] = | |
| 229 "precision mediump float; \n" | |
| 230 "varying vec2 v_texCoord; \n" | |
| 231 "uniform sampler2D s_texture; \n" | |
| 232 "void main() \n" | |
| 233 "{ \n" | |
| 234 " gl_FragColor = texture2D( s_texture, v_texCoord );\n" | |
| 235 "} \n"; | |
| 236 | |
| 237 // Load the shaders and get a linked program object | |
| 238 userData->programObject = esLoadProgram ( vShaderStr, fShaderStr ); | |
| 239 | |
| 240 // Get the attribute locations | |
| 241 userData->positionLoc = glGetAttribLocation ( userData->programObject, "a_pos
ition" ); | |
| 242 userData->texCoordLoc = glGetAttribLocation ( userData->programObject, "a_tex
Coord" ); | |
| 243 | |
| 244 // Get the sampler location | |
| 245 userData->samplerLoc = glGetUniformLocation ( userData->programObject, "s_tex
ture" ); | |
| 246 | |
| 247 // Get the offset location | |
| 248 userData->offsetLoc = glGetUniformLocation( userData->programObject, "u_offse
t" ); | |
| 249 | |
| 250 // Load the texture | |
| 251 userData->textureId = CreateMipMappedTexture2D (); | |
| 252 | |
| 253 glClearColor ( 0.0f, 0.0f, 0.0f, 0.0f ); | |
| 254 return TRUE; | |
| 255 } | |
| 256 | |
| 257 /// | |
| 258 // Draw a triangle using the shader pair created in Init() | |
| 259 // | |
| 260 void Draw ( ESContext *esContext ) | |
| 261 { | |
| 262 UserData *userData = esContext->userData; | |
| 263 GLfloat vVertices[] = { -0.5f, 0.5f, 0.0f, 1.5f, // Position 0 | |
| 264 0.0f, 0.0f, // TexCoord 0 | |
| 265 -0.5f, -0.5f, 0.0f, 0.75f, // Position 1 | |
| 266 0.0f, 1.0f, // TexCoord 1 | |
| 267 0.5f, -0.5f, 0.0f, 0.75f, // Position 2 | |
| 268 1.0f, 1.0f, // TexCoord 2 | |
| 269 0.5f, 0.5f, 0.0f, 1.5f, // Position 3 | |
| 270 1.0f, 0.0f // TexCoord 3 | |
| 271 }; | |
| 272 GLushort indices[] = { 0, 1, 2, 0, 2, 3 }; | |
| 273 | |
| 274 // Set the viewport | |
| 275 glViewport ( 0, 0, esContext->width, esContext->height ); | |
| 276 | |
| 277 // Clear the color buffer | |
| 278 glClear ( GL_COLOR_BUFFER_BIT ); | |
| 279 | |
| 280 // Use the program object | |
| 281 glUseProgram ( userData->programObject ); | |
| 282 | |
| 283 // Load the vertex position | |
| 284 glVertexAttribPointer ( userData->positionLoc, 4, GL_FLOAT, | |
| 285 GL_FALSE, 6 * sizeof(GLfloat), vVertices ); | |
| 286 // Load the texture coordinate | |
| 287 glVertexAttribPointer ( userData->texCoordLoc, 2, GL_FLOAT, | |
| 288 GL_FALSE, 6 * sizeof(GLfloat), &vVertices[4] ); | |
| 289 | |
| 290 glEnableVertexAttribArray ( userData->positionLoc ); | |
| 291 glEnableVertexAttribArray ( userData->texCoordLoc ); | |
| 292 | |
| 293 // Bind the texture | |
| 294 glActiveTexture ( GL_TEXTURE0 ); | |
| 295 glBindTexture ( GL_TEXTURE_2D, userData->textureId ); | |
| 296 | |
| 297 // Set the sampler texture unit to 0 | |
| 298 glUniform1i ( userData->samplerLoc, 0 ); | |
| 299 | |
| 300 // Draw quad with nearest sampling | |
| 301 glTexParameteri ( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST ); | |
| 302 glUniform1f ( userData->offsetLoc, -0.6f ); | |
| 303 glDrawElements ( GL_TRIANGLES, 6, GL_UNSIGNED_SHORT, indices ); | |
| 304 | |
| 305 // Draw quad with trilinear filtering | |
| 306 glTexParameteri ( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINE
AR ); | |
| 307 glUniform1f ( userData->offsetLoc, 0.6f ); | |
| 308 glDrawElements ( GL_TRIANGLES, 6, GL_UNSIGNED_SHORT, indices ); | |
| 309 | |
| 310 eglSwapBuffers ( esContext->eglDisplay, esContext->eglSurface ); | |
| 311 } | |
| 312 | |
| 313 /// | |
| 314 // Cleanup | |
| 315 // | |
| 316 void ShutDown ( ESContext *esContext ) | |
| 317 { | |
| 318 UserData *userData = esContext->userData; | |
| 319 | |
| 320 // Delete texture object | |
| 321 glDeleteTextures ( 1, &userData->textureId ); | |
| 322 | |
| 323 // Delete program object | |
| 324 glDeleteProgram ( userData->programObject ); | |
| 325 } | |
| 326 | |
| 327 | |
| 328 int main ( int argc, char *argv[] ) | |
| 329 { | |
| 330 ESContext esContext; | |
| 331 UserData userData; | |
| 332 | |
| 333 esInitContext ( &esContext ); | |
| 334 esContext.userData = &userData; | |
| 335 | |
| 336 esCreateWindow ( &esContext, "MipMap 2D", 320, 240, ES_WINDOW_RGB ); | |
| 337 | |
| 338 if ( !Init ( &esContext ) ) | |
| 339 return 0; | |
| 340 | |
| 341 esRegisterDrawFunc ( &esContext, Draw ); | |
| 342 | |
| 343 esMainLoop ( &esContext ); | |
| 344 | |
| 345 ShutDown ( &esContext ); | |
| 346 } | |
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Chromium Code Reviews
Issue 543002:
Renamed gles_book_examples to gles2_book to make it shorter and more correct.... (Closed)
Base URL: svn://svn.chromium.org/chrome/trunk/src/