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Diffstat (limited to 'samples/gles2_book/PostSubBuffer/PostSubBuffer.c')
| -rw-r--r-- | samples/gles2_book/PostSubBuffer/PostSubBuffer.c | 204 |
1 files changed, 204 insertions, 0 deletions
diff --git a/samples/gles2_book/PostSubBuffer/PostSubBuffer.c b/samples/gles2_book/PostSubBuffer/PostSubBuffer.c new file mode 100644 index 00000000..0096ec31 --- /dev/null +++ b/samples/gles2_book/PostSubBuffer/PostSubBuffer.c @@ -0,0 +1,204 @@ +// Based on a sample from: +// +// 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 +// + +// PostSubBuffer.c +// +// This is a simple example that draws a rotating cube in perspective +// using a vertex shader to transform the object, posting only a subrectangle +// to the window surface. +// +#include <stdlib.h> +#include "esUtil.h" + +#define WINDOW_WIDTH 320 +#define WINDOW_HEIGHT 240 + +typedef struct +{ + // Handle to a program object + GLuint programObject; + + // Attribute locations + GLint positionLoc; + + // Uniform locations + GLint mvpLoc; + + // Vertex daata + GLfloat *vertices; + GLushort *indices; + int numIndices; + + // Rotation angle + GLfloat angle; + + // MVP matrix + ESMatrix mvpMatrix; +} UserData; + +/// +// Initialize the shader and program object +// +int Init ( ESContext *esContext ) +{ + UserData *userData = esContext->userData; + GLbyte vShaderStr[] = + "uniform mat4 u_mvpMatrix; \n" + "attribute vec4 a_position; \n" + "void main() \n" + "{ \n" + " gl_Position = u_mvpMatrix * a_position; \n" + "} \n"; + + GLbyte fShaderStr[] = + "precision mediump float; \n" + "void main() \n" + "{ \n" + " gl_FragColor = vec4( 1.0, 0.0, 0.0, 1.0 ); \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" ); + + // Get the uniform locations + userData->mvpLoc = glGetUniformLocation( userData->programObject, "u_mvpMatrix" ); + + // Generate the vertex data + userData->numIndices = esGenCube( 1.0, &userData->vertices, + NULL, NULL, &userData->indices ); + + // Starting rotation angle for the cube + userData->angle = 45.0f; + + // Clear the whole window surface. + glClearColor ( 0.0f, 0.0f, 1.0f, 0.0f ); + glClear ( GL_COLOR_BUFFER_BIT ); + eglSwapBuffers ( esContext->eglDisplay, esContext->eglSurface ); + + glClearColor ( 0.0f, 0.0f, 0.0f, 0.0f ); + return TRUE; +} + + +/// +// Update MVP matrix based on time +// +void Update ( ESContext *esContext, float deltaTime ) +{ + UserData *userData = (UserData*) esContext->userData; + ESMatrix perspective; + ESMatrix modelview; + float aspect; + + // Compute a rotation angle based on time to rotate the cube + userData->angle += ( deltaTime * 40.0f ); + if( userData->angle >= 360.0f ) + userData->angle -= 360.0f; + + // Compute the window aspect ratio + aspect = (GLfloat) esContext->width / (GLfloat) esContext->height; + + // Generate a perspective matrix with a 60 degree FOV + esMatrixLoadIdentity( &perspective ); + esPerspective( &perspective, 60.0f, aspect, 1.0f, 20.0f ); + + // Generate a model view matrix to rotate/translate the cube + esMatrixLoadIdentity( &modelview ); + + // Translate away from the viewer + esTranslate( &modelview, 0.0, 0.0, -2.0 ); + + // Rotate the cube + esRotate( &modelview, userData->angle, 1.0, 0.0, 1.0 ); + + // Compute the final MVP by multiplying the + // modevleiw and perspective matrices together + esMatrixMultiply( &userData->mvpMatrix, &modelview, &perspective ); +} + +/// +// 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 ); + + // Use the program object + glUseProgram ( userData->programObject ); + + // Load the vertex position + glVertexAttribPointer ( userData->positionLoc, 3, GL_FLOAT, + GL_FALSE, 3 * sizeof(GLfloat), userData->vertices ); + + glEnableVertexAttribArray ( userData->positionLoc ); + + + // Load the MVP matrix + glUniformMatrix4fv( userData->mvpLoc, 1, GL_FALSE, (GLfloat*) &userData->mvpMatrix.m[0][0] ); + + // Draw the cube + glDrawElements ( GL_TRIANGLES, userData->numIndices, GL_UNSIGNED_SHORT, userData->indices ); + + eglPostSubBufferNV ( esContext->eglDisplay, esContext->eglSurface, 60, 60, WINDOW_WIDTH - 120, WINDOW_HEIGHT - 120 ); +} + +/// +// Cleanup +// +void ShutDown ( ESContext *esContext ) +{ + UserData *userData = esContext->userData; + + if ( userData->vertices != NULL ) + { + free ( userData->vertices ); + } + + if ( userData->indices != NULL ) + { + free ( userData->indices ); + } + + // Delete program object + glDeleteProgram ( userData->programObject ); +} + + +int main ( int argc, char *argv[] ) +{ + ESContext esContext; + UserData userData; + + esInitContext ( &esContext ); + esContext.userData = &userData; + + esCreateWindow ( &esContext, TEXT("Simple Vertex Shader"), WINDOW_WIDTH, WINDOW_HEIGHT, ES_WINDOW_RGB | ES_WINDOW_POST_SUB_BUFFER_SUPPORTED ); + + if ( !Init ( &esContext ) ) + return 0; + + esRegisterDrawFunc ( &esContext, Draw ); + esRegisterUpdateFunc ( &esContext, Update ); + + esMainLoop ( &esContext ); + + ShutDown ( &esContext ); +} |