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Problem with gles 2 textures


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#1 GorbGorb   Members   -  Reputation: 112

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Posted 30 August 2012 - 03:39 AM

Hi, I'm learning gles 2 android ndk at the moment, but I can't display a texture. I expect my code to render a black texture on the screen, but all I get is some color garbage. This is my rendering routine:
[source lang="cpp"] gl_context::create_context( s ); glViewport( 0 , 0 , gl_context::width() , gl_context::height() ); glClearColor( 0.0f , 0.0f , 0.0f , 0.0f ); GLuint shader_program = 0; GLuint position = 0; GLuint texture_coord = 1; GLuint sampler = 0; const char* vertex_shader_source = "attribute vec4 position; \n" "attribute vec2 a_texture_coord; \n" "varying vec2 v_texture_coord; \n" "void main() \n" "{ \n" " gl_Position = position; \n" " v_texture_coord = a_texture_coord; \n" "} \n"; const char* fragment_shader_source = "precision mediump float; \n" "uniform sampler2D sampler; \n" "varying vec2 v_texture_coord; \n" "void main() \n" "{ \n" " gl_FragColor = texture2D( sampler , v_texture_coord );" //" gl_FragColor = vec4( 1.0 , 0.0 , 0.0 , 1.0 );" //uncommenting this results in a red screen, so I guess I have a valid gles 2 context "} \n"; GLuint vertex_shader = glCreateShader( GL_VERTEX_SHADER ); glShaderSource( vertex_shader , 1 , &vertex_shader_source , 0 ); glCompileShader( vertex_shader ); GLuint fragment_shader = glCreateShader( GL_FRAGMENT_SHADER ); glShaderSource( fragment_shader , 1 , &fragment_shader_source , 0 ); glCompileShader( fragment_shader ); shader_program = glCreateProgram(); glAttachShader( shader_program , vertex_shader ); glAttachShader( shader_program , fragment_shader ); glBindAttribLocation( shader_program , position , "position" ); glBindAttribLocation( shader_program , texture_coord , "a_texture_coord" ); glLinkProgram( shader_program ); glUseProgram( shader_program ); sampler = glGetUniformLocation( shader_program , "sampler" ); glActiveTexture( GL_TEXTURE0 ); glBindTexture( GL_TEXTURE_2D , 0 ) ; std::vector< GLubyte > buffer( 64 * 64 * 3 , 0 ); glTexImage2D( GL_TEXTURE_2D , 0 , GL_RGB , 64 , 64 , 0 , GL_RGB , GL_UNSIGNED_BYTE , buffer.data() ); glUniform1i( sampler , 0 ); glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT ); const GLfloat vertex_positions[] = { -1.0f, -1.0f, 1.0f, -1.0f, -1.0f, 1.0f, 1.0f, 1.0f, }; const GLfloat texture_coords[] = { 1.0f, 1.0f, 1.0f, 0.0f, 0.0f, 1.0f, 0.0f, 0.0f, }; glVertexAttribPointer( position , 2 , GL_FLOAT , GL_FALSE , 0 , vertex_positions ); glEnableVertexAttribArray( position ); glVertexAttribPointer( texture_coord , 2 , GL_FLOAT , GL_FALSE , 0 , texture_coords ); glEnableVertexAttribArray( texture_coord ); glDrawArrays( GL_TRIANGLE_STRIP , 0 , 4 ); glDisableVertexAttribArray( position ); glDisableVertexAttribArray( texture_coord ); gl_context::swap_buffers();[/source]

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