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Hajime Hoshi 2014-12-22 01:54:07 +09:00
parent 99434fa9d3
commit 89c6e7c371
1 changed files with 5 additions and 1 deletions
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internal/opengl/internal/shader/shader.go
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@ -86,7 +86,11 @@ void main(void) {
vec4 color1 = texture2D(texture1, vertex_out_tex_coord1);
color0 = (color_matrix * color0) + color_matrix_translation;
// Photoshop-like RGBA blending
// Photoshop-like RGBA blending.
//
// NOTE: If the textures are alpha premultiplied, this calc would be much simpler,
// but the color matrix must be applied to the straight alpha colors.
// Thus, straight alpha colors are used in Ebiten.
gl_FragColor.a = color0.a + (1.0 - color0.a) * color1.a;
gl_FragColor.rgb = (color0.a * color0.rgb + (1.0 - color0.a) * color1.a * color1.rgb) / gl_FragColor.a;
}