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debonair
10-09-2012, 06:28 AM
Hi,
I am using texture buffer objects for the texturing, the problem is that when i pass diff values for pixels it renders max values and there is no change in the intensity of color. e.g. my texture data type is GLubyte, when i pass 34, 43 values as color it renders color with highest intensity values which is same as 255.

here is my code:

Vert shader:



in vec2 a_position;
uniform float offset_x;
void main()
{
gl_Position = vec4(a_position.x + offset_x, a_position.y, 1.0, 1.0);
}


Frag shader:


out vec4 Color;
uniform isamplerBuffer sampler;
uniform int index;
void main()
{
Color=texelFetch(sampler,index);

}





GLubyte arr[]={128,5,250};
glGenBuffers(1,&bufferid);

glBindBuffer(GL_TEXTURE_BUFFER,bufferid);

glBufferData(GL_TEXTURE_BUFFER,sizeof(arr),arr,GL_ STATIC_DRAW);
glBindBuffer(GL_TEXTURE_BUFFER,0);

glGenTextures(1, &buffer_texture);

glBindTexture(GL_TEXTURE_BUFFER, buffer_texture);
glTexBuffer(GL_TEXTURE_BUFFER, GL_R8, bufferid);


glUniform1f(glGetUniformLocation(shader_data.psId,"offset_x"),0.0f);
glUniform1i(glGetUniformLocation(shader_data.psId,"sampler"),0);
glUniform1i(glGetUniformLocation(shader_data.psId,"index"),0);

glGenBuffers(1,&bufferid1);

glBindBuffer(GL_ARRAY_BUFFER,bufferid1);
glBufferData(GL_ARRAY_BUFFER,sizeof(vertices4),ver tices4,GL_STATIC_DRAW);

attr_vertex = glGetAttribLocation(shader_data.psId, "a_position");

glVertexAttribPointer(attr_vertex, 2 , GL_FLOAT, GL_FALSE ,0, 0);

glEnableVertexAttribArray(attr_vertex);

glDrawArrays(GL_TRIANGLE_FAN,0,4);

glUniform1i(glGetUniformLocation(shader_data.psId,"index"),1);

glVertexAttribPointer(attr_vertex, 2 , GL_FLOAT, GL_FALSE ,0,(void *)(32) );

glDrawArrays(GL_TRIANGLE_FAN,0,4);

glUniform1i(glGetUniformLocation(shader_data.psId,"index"),2);

glVertexAttribPointer(attr_vertex, 2 , GL_FLOAT, GL_FALSE ,0,(void *)(64) );

glDrawArrays(GL_TRIANGLE_FAN,0,4);


In this case it draws all the 3 squares with dark red color and no change in the intensity of the color.