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//
// Book: OpenGL(R) ES 2.0 Programming Guide
// Authors: Aaftab Munshi, Dan Ginsburg, Dave Shreiner
// ISBN-10: 0321502795
// ISBN-13: 9780321502797
// Publisher: Addison-Wesley Professional
// URLs: http://safari.informit.com/9780321563835
// http://www.opengles-book.com
//
// Simple_TextureCubemap.c
//
// This is a simple example that draws a sphere with a cubemap image applied.
//
#include <stdlib.h>
#include "esUtil.h"
typedef struct
{
// Handle to a program object
GLuint programObject;
// Attribute locations
GLint positionLoc;
GLint normalLoc;
// Sampler location
GLint samplerLoc;
// Texture handle
GLuint textureId;
// Vertex data
int numIndices;
GLfloat *vertices;
GLfloat *normals;
GLushort *indices;
GLuint vertPosObject, vertNormalObject, indicesObject;
} UserData;
///
// Create a simple cubemap with a 1x1 face with a different
// color for each face
GLuint CreateSimpleTextureCubemap( )
{
GLuint textureId;
// Six 1x1 RGB faces
GLubyte cubePixels[6][3] =
{
// Face 0 - Red
255, 0, 0,
// Face 1 - Green,
0, 255, 0,
// Face 3 - Blue
0, 0, 255,
// Face 4 - Yellow
255, 255, 0,
// Face 5 - Purple
255, 0, 255,
// Face 6 - White
255, 255, 255
};
// Generate a texture object
glGenTextures ( 1, &textureId );
// Bind the texture object
glBindTexture ( GL_TEXTURE_CUBE_MAP, textureId );
// Load the cube face - Positive X
glTexImage2D ( GL_TEXTURE_CUBE_MAP_POSITIVE_X, 0, GL_RGB, 1, 1, 0,
GL_RGB, GL_UNSIGNED_BYTE, &cubePixels[0] );
// Load the cube face - Negative X
glTexImage2D ( GL_TEXTURE_CUBE_MAP_NEGATIVE_X, 0, GL_RGB, 1, 1, 0,
GL_RGB, GL_UNSIGNED_BYTE, &cubePixels[1] );
// Load the cube face - Positive Y
glTexImage2D ( GL_TEXTURE_CUBE_MAP_POSITIVE_Y, 0, GL_RGB, 1, 1, 0,
GL_RGB, GL_UNSIGNED_BYTE, &cubePixels[2] );
// Load the cube face - Negative Y
glTexImage2D ( GL_TEXTURE_CUBE_MAP_NEGATIVE_Y, 0, GL_RGB, 1, 1, 0,
GL_RGB, GL_UNSIGNED_BYTE, &cubePixels[3] );
// Load the cube face - Positive Z
glTexImage2D ( GL_TEXTURE_CUBE_MAP_POSITIVE_Z, 0, GL_RGB, 1, 1, 0,
GL_RGB, GL_UNSIGNED_BYTE, &cubePixels[4] );
// Load the cube face - Negative Z
glTexImage2D ( GL_TEXTURE_CUBE_MAP_NEGATIVE_Z, 0, GL_RGB, 1, 1, 0,
GL_RGB, GL_UNSIGNED_BYTE, &cubePixels[5] );
// Set the filtering mode
glTexParameteri ( GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MIN_FILTER, GL_NEAREST );
glTexParameteri ( GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MAG_FILTER, GL_NEAREST );
return textureId;
}
#include <stdio.h>
///
// Initialize the shader and program object
//
int Init ( ESContext *esContext )
{
//esContext->userData = malloc(sizeof(UserData));
UserData *userData = esContext->userData;
GLbyte vShaderStr[] =
"attribute vec4 a_position; \n"
"attribute vec3 a_normal; \n"
"varying vec3 v_normal; \n"
"void main() \n"
"{ \n"
" gl_Position = a_position; \n"
" v_normal = a_normal; \n"
"} \n";
GLbyte fShaderStr[] =
"precision mediump float; \n"
"varying vec3 v_normal; \n"
"uniform samplerCube s_texture; \n"
"void main() \n"
"{ \n"
" gl_FragColor = textureCube( s_texture, v_normal );\n"
"} \n";
// Load the shaders and get a linked program object
userData->programObject = esLoadProgram ( vShaderStr, fShaderStr );
// Get the attribute locations
userData->positionLoc = glGetAttribLocation ( userData->programObject, "a_position" );
userData->normalLoc = glGetAttribLocation ( userData->programObject, "a_normal" );
// Get the sampler locations
userData->samplerLoc = glGetUniformLocation ( userData->programObject, "s_texture" );
// Load the texture
userData->textureId = CreateSimpleTextureCubemap ();
// Generate the vertex data
userData->numIndices = esGenSphere ( 20, 0.75f, &userData->vertices, &userData->normals,
NULL, &userData->indices );
// Generate the VBOs
glGenBuffers(1, &userData->vertPosObject);
glBindBuffer(GL_ARRAY_BUFFER, userData->vertPosObject);
glBufferData(GL_ARRAY_BUFFER, 21 * 21 * 4 * 3, userData->vertices, GL_STATIC_DRAW );
glGenBuffers(1, &userData->vertNormalObject);
glBindBuffer(GL_ARRAY_BUFFER, userData->vertNormalObject );
glBufferData(GL_ARRAY_BUFFER, 21 * 21 * 4 * 3, userData->normals, GL_STATIC_DRAW );
glGenBuffers(1, &userData->indicesObject);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, userData->indicesObject );
glBufferData(GL_ELEMENT_ARRAY_BUFFER, 2 * userData->numIndices, userData->indices, GL_STATIC_DRAW );
glClearColor ( 0.0f, 0.0f, 0.0f, 1.0f );
return GL_TRUE;
}
///
// Draw a triangle using the shader pair created in Init()
//
void Draw ( ESContext *esContext )
{
UserData *userData = esContext->userData;
// Set the viewport
glViewport ( 0, 0, esContext->width, esContext->height );
// Clear the color buffer
glClear ( GL_COLOR_BUFFER_BIT );
glCullFace ( GL_BACK );
glEnable ( GL_CULL_FACE );
// Use the program object
glUseProgram ( userData->programObject );
// Load the vertex position
glBindBuffer ( GL_ARRAY_BUFFER, userData->vertPosObject );
glVertexAttribPointer ( userData->positionLoc, 3, GL_FLOAT,
GL_FALSE, 0, 0 );
// Load the normal
glBindBuffer ( GL_ARRAY_BUFFER, userData->vertNormalObject );
glVertexAttribPointer ( userData->normalLoc, 3, GL_FLOAT,
GL_FALSE, 0, 0 );
glEnableVertexAttribArray ( userData->positionLoc );
glEnableVertexAttribArray ( userData->normalLoc );
// Bind the texture
glActiveTexture ( GL_TEXTURE0 );
glBindTexture ( GL_TEXTURE_CUBE_MAP, userData->textureId );
// Set the sampler texture unit to 0
glUniform1i ( userData->samplerLoc, 0 );
glBindBuffer ( GL_ELEMENT_ARRAY_BUFFER, userData->indicesObject );
glDrawElements ( GL_TRIANGLES, userData->numIndices,
GL_UNSIGNED_SHORT, 0 );
}
///
// Cleanup
//
void ShutDown ( ESContext *esContext )
{
UserData *userData = esContext->userData;
// Delete texture object
glDeleteTextures ( 1, &userData->textureId );
// Delete program object
glDeleteProgram ( userData->programObject );
free ( userData->vertices );
free ( userData->normals );
//free ( esContext->userData);
}
int main ( int argc, char *argv[] )
{
ESContext esContext;
UserData userData;
esInitContext ( &esContext );
esContext.userData = &userData;
esCreateWindow ( &esContext, "Simple Texture Cubemap", 320, 240, ES_WINDOW_RGB );
if ( !Init ( &esContext ) )
return 0;
esRegisterDrawFunc ( &esContext, Draw );
esMainLoop ( &esContext );
ShutDown ( &esContext );
}
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