[vlc-devel] [PATCH 01/18] opengl: use common fragment shader for Android

[Romain Vimont]

On Fri, Dec 20, 2019 at 03:48:43PM +0100, Romain Vimont wrote:
> @@ -315,12 +316,13 @@ static GLuint BuildVertexShader(const opengl_tex_converter_t *tc,
>          "attribute vec4 MultiTexCoord0;\n"
>          "%s%s"
>          "attribute vec3 VertexPosition;\n"
> +        "uniform mat4 TransformMatrix;\n"
>          "uniform mat4 OrientationMatrix;\n"
>          "uniform mat4 ProjectionMatrix;\n"
>          "uniform mat4 ZoomMatrix;\n"
>          "uniform mat4 ViewMatrix;\n"
>          "void main() {\n"
> -        " TexCoord0 = vec4(OrientationMatrix * MultiTexCoord0).st;\n"
> +        " TexCoord0 = vec4(TransformMatrix * OrientationMatrix * MultiTexCoord0).st;\n"

Actually, the multiplication order must be reversed:

    vec4(OrientationMatrix * TransformMatrix * MultiTexCoord0).st

TransformMatrix represents how the coordinates of the texture
initialized by the converter must be transformed, so it must be applied
first.