Graphics Reference
In-Depth Information
This section should help you better understand the limitations of the
OpenGL ES 3.0 Shading Language and appreciate how to write vertex shaders
that should compile and run on most OpenGL ES 3.0 implementations.
We now present a few examples that demonstrate how to implement the
following features in a vertex shader:
• Transforming vertex position with a matrix
• Lighting computations to generate per-vertex diffuse and specular color
• Texture coordinate generation
• Vertex skinning
• Displacing vertex position with a texture lookup value
These features represent typical use cases that OpenGL ES 3.0 applications
will want to perform in a vertex shader.
Example 8-1 describes a simple vertex shader written using the OpenGL
ES Shading Language. The vertex shader takes a position and its associated
Example 8-1
Vertex Shader with Matrix Transform for the Position
#version 300 es
// uniforms used by the vertex shader
uniform mat4 u_mvpMatrix; // matrix to convert position from
// model space to clip space
// attribute inputs to the vertex shader
layout(location = 0) in vec4 a_position; // input position value
layout(location = 1) in vec4 a_color; // input color
// vertex shader output, input to the fragment shader
out vec4 v_color;
void main()
{
v_color = a_color;
gl_Position = u_mvpMatrix * a_position;
}
