a53163660f
Don't globally set float precision to mediump, only fragment shaders need that and defining it for vertex shaders causes tilemap cracks. Also manually define low precision for variables that hold color / alpha values.
33 lines
665 B
GLSL
33 lines
665 B
GLSL
/* Shader for approximating the way RMXP does bitmap
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* blending via DirectDraw */
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uniform sampler2D source;
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uniform sampler2D destination;
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uniform vec4 subRect;
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uniform lowp float opacity;
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varying vec2 v_texCoord;
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void main()
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{
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vec2 coor = v_texCoord;
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vec2 dstCoor = (coor - subRect.xy) * subRect.zw;
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vec4 srcFrag = texture2D(source, coor);
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vec4 dstFrag = texture2D(destination, dstCoor);
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vec4 resFrag;
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float co1 = srcFrag.a * opacity;
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float co2 = dstFrag.a * (1.0 - co1);
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resFrag.a = co1 + co2;
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if (resFrag.a == 0.0)
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resFrag.rgb = srcFrag.rgb;
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else
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resFrag.rgb = (co1*srcFrag.rgb + co2*dstFrag.rgb) / resFrag.a;
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gl_FragColor = resFrag;
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}
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