When the fragment shader is invoked for a fragment belonging to the primitive in question, v_texCoord in the fragment shader will be the texture coordinate that has been interpolated between the three vertices. the interpolated value passed on to the next stage (e.g. Simply takes the first of the possible texture coordinates and assigns it to the varying variable v_texCoord in the vertex shader, i.e.
Values at the vertices are simply interpolated and the result of the interpolation is passed to the fragment shader. a triangle made up of three vertices, fragments are generated that cover the approximate area the primitive occupies after projection. It’s simple, for each vertexyou can have a zero, one, or multiple texture coordinates. Send to the fragment shader the texture coordinate of the last vertex that pass through the vertex shader …
Opengl 4.3 textures and lighting code#
Seems that I don’t really understand how the shaders works… For me, the following code : So how the fragment shader can access the texture with only one coordinate that come from the vertex shader ? This mean that during rasterisation, texture mapping depend of the three texture coordinates associated with the three vertices. When we send data to opengl we associate to each vertex a texture coordinate with glTexCoord. I don’t understand the meaning of the v_texCoord vertor.
Gl_FragColor = texture2D(tex0, v_texCoord) * v_color Gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex
I try to understand the following texture mapping shader :