Graphics Reference
In-Depth Information
Example 14-25
Create a Depth Texture and Attach It to a Framebuffer
Object
(continued)
glActiveTexture ( GL_TEXTURE0 );
glBindTexture ( GL_TEXTURE_2D, userData−>shadowMapTextureId);
if ( GL_FRAMEBUFFER_COMPLETE !=
glCheckFramebufferStatus ( GL_FRAMEBUFFER ) )
{
return FALSE;
}
glBindFramebuffer ( GL_FRAMEBUFFER, defaultFramebuffer );
return TRUE;
}
3.
Render the scene using a pass-through vertex and fragment shader.
Example 14-26 provides the vertex and fragment shaders used to
render the scene to the depth texture from the point of view of the
light. Both shaders are very simple, as we need simply to record the
fragment depth value into the shadow map texture.
Example 14-26
Rendering to Depth Texture Shaders
// vertex shader
#version 300 es
uniform mat4 u_mvpLightMatrix;
layout(location = 0) in vec4 a_position;
out vec4 v_color;
void main()
{
gl_Position = u_mvpLightMatrix * a_position;
}
// fragment shader
#version 300 es
precision lowp float;
void main()
{
}
To use these shaders, in the host code prior to rendering the scene,
we clear the depth buffer and disable color rendering. To avoid the
creation of a shadow rendering artifact due to a precision problem,
