opengl: Allow using the RGBA shader for the main picture

So far, the RGBA shader has only been used for the subpictures.
On ES2, the fixed function pipeline is not available, so we need to
use the shader for drawing the main picture even if it is RGBA.
Signed-off-by: Martin Storsjö <martin@martin.st>

modules/video_output/opengl.c

@@ -465,6 +465,7 @@ vout_display_opengl_t *vout_display_opengl_New(video_format_t *fmt,
     vgl->tex_type     = GL_UNSIGNED_BYTE;
     /* Use YUV if possible and needed */
     bool need_fs_yuv = false;
+    bool need_fs_rgba = USE_OPENGL_ES == 2;
     float yuv_range_correction = 1.0;
 
     if (max_texture_units >= 3 && supports_shaders && vlc_fourcc_IsYUV(fmt->i_chroma)) {
@@ -520,7 +521,7 @@ vout_display_opengl_t *vout_display_opengl_New(video_format_t *fmt,
     vgl->shader[1] =
     vgl->shader[2] = -1;
     vgl->local_count = 0;
-    if (supports_shaders && need_fs_yuv) {
+    if (supports_shaders && (need_fs_yuv || need_fs_rgba)) {
 #ifdef SUPPORTS_SHADERS
         BuildYUVFragmentShader(vgl, &vgl->shader[0], &vgl->local_count,
                                vgl->local_value, fmt, yuv_range_correction);
@@ -915,13 +916,19 @@ static void DrawWithoutShaders(vout_display_opengl_t *vgl,
 
 #ifdef SUPPORTS_SHADERS
 static void DrawWithShaders(vout_display_opengl_t *vgl,
-                            float *left, float *top, float *right, float *bottom)
+                            float *left, float *top, float *right, float *bottom,
+                            int program)
 {
-    vgl->UseProgram(vgl->program[0]);
-    vgl->Uniform4fv(vgl->GetUniformLocation(vgl->program[0], "Coefficient"), 4, vgl->local_value);
-    vgl->Uniform1i(vgl->GetUniformLocation(vgl->program[0], "Texture0"), 0);
-    vgl->Uniform1i(vgl->GetUniformLocation(vgl->program[0], "Texture1"), 1);
-    vgl->Uniform1i(vgl->GetUniformLocation(vgl->program[0], "Texture2"), 2);
+    vgl->UseProgram(vgl->program[program]);
+    if (program == 0) {
+        vgl->Uniform4fv(vgl->GetUniformLocation(vgl->program[0], "Coefficient"), 4, vgl->local_value);
+        vgl->Uniform1i(vgl->GetUniformLocation(vgl->program[0], "Texture0"), 0);
+        vgl->Uniform1i(vgl->GetUniformLocation(vgl->program[0], "Texture1"), 1);
+        vgl->Uniform1i(vgl->GetUniformLocation(vgl->program[0], "Texture2"), 2);
+    } else {
+        vgl->Uniform1i(vgl->GetUniformLocation(vgl->program[1], "Texture0"), 0);
+        vgl->Uniform4f(vgl->GetUniformLocation(vgl->program[1], "FillColor"), 1.0f, 1.0f, 1.0f, 1.0f);
+    }
 
     static const GLfloat vertexCoord[] = {
         -1.0,  1.0,
@@ -944,13 +951,13 @@ static void DrawWithShaders(vout_display_opengl_t *vgl,
 
         char attribute[20];
         snprintf(attribute, sizeof(attribute), "MultiTexCoord%1d", j);
-        vgl->EnableVertexAttribArray(vgl->GetAttribLocation(vgl->program[0], attribute));
-        vgl->VertexAttribPointer(vgl->GetAttribLocation(vgl->program[0], attribute), 2, GL_FLOAT, 0, 0, textureCoord);
+        vgl->EnableVertexAttribArray(vgl->GetAttribLocation(vgl->program[program], attribute));
+        vgl->VertexAttribPointer(vgl->GetAttribLocation(vgl->program[program], attribute), 2, GL_FLOAT, 0, 0, textureCoord);
     }
     glActiveTexture(GL_TEXTURE0 + 0);
     glClientActiveTexture(GL_TEXTURE0 + 0);
-    vgl->EnableVertexAttribArray(vgl->GetAttribLocation(vgl->program[0], "VertexPosition"));
-    vgl->VertexAttribPointer(vgl->GetAttribLocation(vgl->program[0], "VertexPosition"), 2, GL_FLOAT, 0, 0, vertexCoord);
+    vgl->EnableVertexAttribArray(vgl->GetAttribLocation(vgl->program[program], "VertexPosition"));
+    vgl->VertexAttribPointer(vgl->GetAttribLocation(vgl->program[program], "VertexPosition"), 2, GL_FLOAT, 0, 0, vertexCoord);
 
     glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
 }
@@ -992,8 +999,10 @@ int vout_display_opengl_Display(vout_display_opengl_t *vgl,
     }
 
 #ifdef SUPPORTS_SHADERS
-    if (vgl->program[0])
-        DrawWithShaders(vgl, left, top ,right, bottom);
+    if (vgl->program[0] && vgl->chroma->plane_count == 3)
+        DrawWithShaders(vgl, left, top, right, bottom, 0);
+    else if (vgl->program[1] && vgl->chroma->plane_count == 1)
+        DrawWithShaders(vgl, left, top, right, bottom, 1);
     else
 #endif
     {