1、正片叠底
shader
// 正片叠底
uniform sampler2D U_MainTexture;
uniform sampler2D U_SubTexture;
varying vec2 M_coord;
void main()
{
vec4 blendColor = texture2D(U_SubTexture, M_coord);
vec4 baseColor = texture2D(U_MainTexture, M_coord);
gl_FragColor = blendColor * baseColor;
}效果图
2、逆正片叠底
shader
// 逆正片叠底
uniform sampler2D U_MainTexture;
uniform sampler2D U_SubTexture;
varying vec2 M_coord;
void main()
{
vec4 blendColor = texture2D(U_SubTexture, M_coord);
vec4 baseColor = texture2D(U_MainTexture, M_coord);
gl_FragColor = vec4(1.0) - (vec4(1.0) - blendColor) * (vec4(1.0) - baseColor);
}效果图
本文出自 “不会飞的纸飞机” 博客，请务必保留此出处http://douzhq.blog.51cto.com/12552184/1931104
基于Qt的OpenGL可编程管线学习（14）- 正片叠底、逆正片叠底
原文：http://douzhq.blog.51cto.com/12552184/1931104