[vlc-devel] [PATCH 14/41] opengl: extract vlc_texture()

[Romain Vimont]

Extract a fragment shader function to provide the pixel color of a
picture from pictures coordinates.

Concretely, it replaces:

    void main(void) {
     vec3 pic_hcoords = vec3(PicCoords, 1.0);
     ...
     gl_FragColor = result * FillColor;
    }

by:

    vec4 vlc_texture(vec2 pic_coords) {
     vec3 pic_hcoords = vec3(pic_coords, 1.0);
     ...
     return result * FillColor;
    }
    void main() {
     gl_FragColor = vlc_texture(PicCoords);
    }
---
 .../video_output/opengl/fragment_shaders.c    | 31 ++++++++++++-------
 1 file changed, 19 insertions(+), 12 deletions(-)

diff --git a/modules/video_output/opengl/fragment_shaders.c b/modules/video_output/opengl/fragment_shaders.c
index 51c5ca6055..9d148028ba 100644
--- a/modules/video_output/opengl/fragment_shaders.c
+++ b/modules/video_output/opengl/fragment_shaders.c
@@ -350,16 +350,19 @@ xyz12_shader_init(struct vlc_gl_renderer *renderer)
         " );"
 
         "varying vec2 PicCoords;"
-        "void main()"
+        "vec4 vlc_texture(vec2 pic_coords)\n"
         "{ "
         " vec4 v_in, v_out;"
-        " v_in  = texture2D(Texture0, PicCoords);"
+        " v_in  = texture2D(Texture0, pic_coords);"
         " v_in = pow(v_in, xyz_gamma);"
         " v_out = matrix_xyz_rgb * v_in ;"
         " v_out = pow(v_out, rgb_gamma) ;"
         " v_out = clamp(v_out, 0.0, 1.0) ;"
-        " gl_FragColor = v_out;"
-        "}";
+        " return v_out;"
+        "}\n"
+        "void main() {\n"
+        " gl_FragColor = vlc_texture(PicCoords);\n"
+        "}\n";
 
     char *code;
     if (asprintf(&code, template, renderer->glsl_version,
@@ -589,12 +592,12 @@ opengl_fragment_shader_init(struct vlc_gl_renderer *renderer, GLenum tex_target,
         ADD("uniform mat4 ConvMatrix;\n");
 
     ADD("uniform vec4 FillColor;\n"
-        "void main(void) {\n");
-    /* Oriented picture coordinates */
-    ADDF(" vec2 pic_txcoords = (TransformMatrix * OrientationMatrix * vec4(%s, 0.0, 1.0)).st;\n", coord_name);
-    /* Homogeneous coordinates */
-    ADD(" vec3 pic_hcoords = vec3(pic_txcoords, 1.0);\n");
-    ADD(" vec2 tex_coords;\n");
+        "vec4 vlc_texture(vec2 pic_coords) {\n"
+        /* Oriented picture coordinates */
+        " vec2 pic_txcoords = (TransformMatrix * OrientationMatrix * vec4(pic_coords, 0.0, 1.0)).st;\n"
+        /* Homogeneous coords */
+        " vec3 pic_hcoords = vec3(pic_txcoords, 1.0);\n"
+        " vec2 tex_coords;\n");
 
     if (tex_target == GL_TEXTURE_RECTANGLE)
     {
@@ -645,8 +648,12 @@ opengl_fragment_shader_init(struct vlc_gl_renderer *renderer, GLenum tex_target,
     }
 #endif
 
-    ADD(" gl_FragColor = result * FillColor;\n"
-        "}");
+    ADD(" return result * FillColor;\n"
+        "}\n");
+
+    ADDF("void main() {\n"
+        " gl_FragColor = vlc_texture(%s);\n"
+        "}\n", coord_name);
 
 #undef ADD
 #undef ADDF
-- 
2.25.0