glsl shader texture atlas

shader

#version 320 es
precision highp float;

in  vec2 TexCoord;
out vec4 FragColor;

// texture sampler
uniform sampler2D texture_diffuse1;

uniform vec2 textureOffset;

void main()
{
	vec2 position = vec2(4.0/8.0, 1.0/8.0);
	vec2 size     = vec2(1.0/8.0, 1.0/8.0);
	
	// 计算1，显示清晰
	vec2 uv = position + size * fract(TexCoord);
	FragColor = texture(texture_diffuse1, uv);
	
	// 计算2， 显示模糊
	vec2 dx = dFdx(TexCoord);
	vec2 dy = dFdy(TexCoord);
	vec2 uv = position + size * fract(TexCoord);
	FragColor = textureGrad(texture_diffuse1, uv, dx, dy);
	
}

参考

• Repeat Tile From Texture Atlas
• Texture atlases, wrapping and mip mapping