Graphics Reference
In-Depth Information
space. To do so, the vertex shader passes the normal, binormal, and
tangent as varyings into the fragment shader so that a tangent matrix can
be constructed.
The fragment shader listing for the environment mapping sample is
provided in Example 14-4.
Example 14-4
Environment Mapping Fragment Shader
#version 300 es
precision mediump float;
uniform vec4 u_ambient;
uniform vec4 u_specular;
uniform vec4 u_diffuse;
uniform float u_specularPower;
uniform sampler2D s_baseMap;
uniform sampler2D s_bumpMap;
uniform samplerCube s_envMap;
in vec2 v_texcoord;
in vec3 v_lightDirection;
in vec3 v_normal;
in vec3 v_binormal;
in vec3 v_tangent;
layout(location = 0) out vec4 fragColor;
void main( void )
{
// Fetch base map color
vec4 baseColor = texture( s_baseMap, v_texcoord );
// Fetch the tangent space normal from normal map
vec3 normal = texture( s_bumpMap, v_texcoord ).xyz;
// Scale and bias from [0, 1] to [−1, 1]
normal = normal * 2.0 − 1.0;
// Construct a matrix to transform from tangent to
// world space
mat3 tangentToWorldMat = mat3( v_tangent,
v_binormal,
v_normal );
// Transform normal to world space and normalize
normal = normalize( tangentToWorldMat * normal );
// Normalize the light direction
vec3 lightDirection = normalize( v_lightDirection );
