gl_FragColor = mix(FirstTextureColor, SecondTextureColor, coeff);
gl_FragColor = mix(FirstTextureColor, SecondTextureColor, coeff);
Where:
FirstTextureColor is a color returned by texture2D(<first texture>,...);
SecondTextureColor is a color returned by texture2D(<second texture>,...);
coeff -> X% of second texture and (100 - X)% of first texture.
Best wishes, FXACE.
For example, how can I get coeff, eg. % of alpha in given point? Could you please write me whole shader?
//vertex shader
void main()
{
gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;
gl_TexCoord[0].xy = gl_MultiTexCoord0.xy;
}
// fragment/pixel shader
uniform sampler2D firstGrassTexture;
uniform sampler2D secondGrassTexture;
uniform sampler2D maskTexture;
void main()
{
gl_FragColor = mix(texture2D(firstGrassTexture,gl_TexCoord[0].xy), texture2D(secondGrassTexture,gl_TexCoord[0].xy), texture2D(maskTexture,gl_TexCoord[0].xy).a);
}
GLhadleARB shaderProgram; // somewhere defined in your application (of course it must be loaded)
glUseProgramObjectARB(shaderProgram);
glUniform1iARB(glGetUniformLocationARB(shaderProgram,"firstGrassTexture"),0);
glUniform1iARB(glGetUniformLocationARB(shaderProgram,"secondGrassTexture"),1);
glUniform1iARB(glGetUniformLocationARB(shaderProgram,"maskTexture"),2);
glUseProgramObjectARB(0);
glActiveTextureARB(GL_TEXTURE0_ARB);
glBindTexture(...);// here you bind first grass texture
glActiveTextureARB(GL_TEXTURE1_ARB);
glBindTexture(...);// here you bind second grass texture
glActiveTextureARB(GL_TEXTURE2_ARB);
glBindTexture(...);// here you bind mask texture
glActiveTextureARB(GL_TEXTURE0_ARB);
glUseProgramObjectARB(shaderProgram);
Draw the mesh
glUseProgramObjectARB(0);// disable using shader (maybe you have some object below which you want to draw them without using shaders
gl_FragColor = mix(texture2D(firstGrassTexture,gl_TexCoord[0].xy), texture2D(secondGrassTexture,gl_TexCoord[0].xy), texture2D(maskTexture,gl_TexCoord[0].xy).a);
