evas: Fix masking with window rotation, take 2

The first patch did not work for maps. This explains why the
original code was so weird. But it actually made sense.

After struggling a bit I realized that we really just need
to shuffle around the pixel position on the window to map that
of the position in the canvas (unrotate it).

Note that compatibility with GLSL-ES (for OpenGL ES) implies
we can not use an array initializer like:
  vec2 pos[4] = vec2[4](a,b,c,d);
So the code could probably be optimized. But at least this works.

This patch also avoids calling glGetUniformLocation again and
again.

src/modules/evas/engines/gl_common/evas_gl_common.h

@@ -103,6 +103,9 @@ typedef Eina_Bool (*evas_gl_make_current_cb)(void *engine_data, void *doit);
 struct _Evas_GL_Program
 {
    unsigned int flags, hitcount, tex_count;
+   struct {
+      GLuint mvp, rotation_id;
+   } uniform;
    GLuint prog;
 
    Eina_Bool reset : 1;

src/modules/evas/engines/gl_common/evas_gl_context.c

@@ -726,17 +726,11 @@ _evas_gl_common_viewport_set(Evas_Engine_GL_Context *gc)
    eina_iterator_free(it);
 
    if (gc->state.current.prog != PRG_INVALID)
-     /*
      {
-        glUseProgram(gc->shared->shader[0].prog);
-        glUniformMatrix4fv(glGetUniformLocation(gc->shared->shader[0].prog, "mvp"), 1, GL_FALSE, gc->shared->proj);
-        gc->shared->shader[0].reset = EINA_FALSE;
-     }
-   else
-   */
-     {
-        glUseProgram(gc->state.current.prog->prog);
-        glUniformMatrix4fv(glGetUniformLocation(gc->state.current.prog->prog, "mvp"), 1, GL_FALSE, gc->shared->proj);
+        prog = gc->state.current.prog;
+        glUseProgram(prog->prog);
+        glUniform1i(prog->uniform.rotation_id, gc->rot / 90);
+        glUniformMatrix4fv(prog->uniform.mvp, 1, GL_FALSE, gc->shared->proj);
      }
 }
 
@@ -1442,9 +1436,20 @@ _push_mask(Evas_Engine_GL_Context *gc, const int pn, int nm, Evas_GL_Texture *mt
    if (!gw || !gh || !mw || !mh || !mtex->pt->w || !mtex->pt->h)
      return EINA_FALSE;
 
-   /* vertex shader:
-    * vec4 mask_Position = mvp * vertex * vec4(0.5, sign(mask_coord.w) * 0.5, 0.5, 0.5) + vec4(0.5, 0.5, 0, 0);
-    * tex_m = mask_Position.xy * abs(mask_coord.zw) + mask_coord.xy;
+   /* Vertex shader:
+    *
+    * INPUTS:
+    *   vec4 mask_coord = vec4(glmx, glmy, glmw, glmh);
+    *   int rotation_id = gc->rot / 90;
+    *
+    * CODE:
+    *   vec4 mask_Position = mvp * vertex * vec4(0.5, sign(mask_coord.w) * 0.5, 0.5, 0.5) + vec4(0.5, 0.5, 0, 0);
+    *   vec2 pos[4]; // no ctor-style init because of GLSL-ES (version 100)
+    *   pos[0] = vec2(mask_Position.xy);
+    *   pos[1] = vec2(1.0 - mask_Position.y, mask_Position.x);
+    *   pos[2] = vec2(1.0 - mask_Position.xy);
+    *   pos[3] = vec2(mask_Position.y, 1.0 - mask_Position.x);
+    *   tex_m = pos[rotation_id].xy * abs(mask_coord.zw) + mask_coord.xy;
     */
    glmx = (double)((mtex->x * mw) - (mtex->w * mx)) / (double)(mw * mtex->pt->w);
    glmy = (double)((mtex->y * mh) - (mtex->h * my)) / (double)(mh * mtex->pt->h);
@@ -1465,13 +1470,6 @@ _push_mask(Evas_Engine_GL_Context *gc, const int pn, int nm, Evas_GL_Texture *mt
         PUSH_MASKSAM(pn, samx, samy, cnt);
      }
 
-   /*
-   DBG("%d,%d %dx%d --> %f , %f - %f x %f [gc %dx%d, tex %d,%d %dx%d, pt %dx%d]",
-       mx, my, mw, mh,
-       glmx, glmy, glmw, glmh,
-       gc->w, gc->h, mtex->x, mtex->y, mtex->w, mtex->h, mtex->pt->w, mtex->pt->h);
-   */
-
    return EINA_TRUE;
 }
 
@@ -3032,7 +3030,8 @@ shader_array_flush(Evas_Engine_GL_Context *gc)
              glUseProgram(prog->prog);
              if (prog->reset)
                {
-                  glUniformMatrix4fv(glGetUniformLocation(prog->prog, "mvp"), 1, GL_FALSE, gc->shared->proj);
+                  glUniform1i(prog->uniform.rotation_id, gc->rot / 90);
+                  glUniformMatrix4fv(prog->uniform.mvp, 1, GL_FALSE, gc->shared->proj);
                   prog->reset = EINA_FALSE;
                }
           }

src/modules/evas/engines/gl_common/evas_gl_shader.c

@@ -160,6 +160,8 @@ _evas_gl_common_shader_program_binary_load(Eet_File *ef, unsigned int flags)
    p->prog = prg;
    p->reset = EINA_TRUE;
    p->bin_saved = EINA_TRUE;
+   p->uniform.mvp = glGetUniformLocation(prg, "mvp");
+   p->uniform.rotation_id = glGetUniformLocation(prg, "rotation_id");
    evas_gl_common_shader_textures_bind(p);
 
 finish:
@@ -566,6 +568,8 @@ evas_gl_common_shader_generate_and_compile(Evas_GL_Shared *shared, unsigned int
    if (p)
      {
         shared->needs_shaders_flush = 1;
+        p->uniform.mvp = glGetUniformLocation(p->prog, "mvp");
+        p->uniform.rotation_id = glGetUniformLocation(p->prog, "rotation_id");
         evas_gl_common_shader_textures_bind(p);
         eina_hash_add(shared->shaders_hash, &flags, p);
      }

src/modules/evas/engines/gl_common/shader/evas_gl_shaders.x

@@ -155,7 +155,7 @@ static const char fragment_glsl[] =
    "     * col\n"
    "#endif\n"
    "#ifdef SHD_MASK\n"
-   "	 * ma\n"
+   "     * ma\n"
    "#endif\n"
    "#ifdef SHD_TEXA\n"
    "     * texture2D(texa, tex_a).r\n"
@@ -174,6 +174,8 @@ static const char vertex_glsl[] =
    "#endif\n"
    "attribute vec4 vertex;\n"
    "uniform mat4 mvp;\n"
+   "/* Window rotation by id 0,1,2,3 (represents 0,90,180,270) */\n"
+   "uniform int rotation_id;\n"
    "/* All except nomul */\n"
    "#ifndef SHD_NOMUL\n"
    "attribute vec4 color;\n"
@@ -278,8 +280,13 @@ static const char vertex_glsl[] =
    "#ifdef SHD_MASK\n"
    "   // mask_coord.w contains the Y-invert flag\n"
    "   // position on screen in [0..1] range of current pixel\n"
-   "   vec4 mask_Position = mvp * vertex * vec4(0.5, sign(mask_coord.w) * 0.5, 0.5, 0.5) + vec4(0.5, 0.5, 0, 0);\n"
-   "   tex_m = mask_Position.xy * abs(mask_coord.zw) + mask_coord.xy;\n"
+   "   vec4 window_Position = mvp * vertex * vec4(0.5, sign(mask_coord.w) * 0.5, 0.5, 0.5) + vec4(0.5, 0.5, 0, 0);\n"
+   "   vec2 pos[4];\n"
+   "   pos[0] = vec2(window_Position.xy);\n"
+   "   pos[1] = vec2(1.0 - window_Position.y, window_Position.x);\n"
+   "   pos[2] = vec2(1.0 - window_Position.xy);\n"
+   "   pos[3] = vec2(window_Position.y, 1.0 - window_Position.x);\n"
+   "   tex_m = pos[rotation_id] * abs(mask_coord.zw) + mask_coord.xy;\n"
    "#endif\n"
    "}\n";
 

src/modules/evas/engines/gl_common/shader/fragment.glsl

@@ -158,7 +158,7 @@ void main()
      * col
 #endif
 #ifdef SHD_MASK
-	 * ma
+     * ma
 #endif
 #ifdef SHD_TEXA
      * texture2D(texa, tex_a).r

src/modules/evas/engines/gl_common/shader/vertex.glsl

@@ -9,6 +9,9 @@ VERTEX_SHADER
 attribute vec4 vertex;
 uniform mat4 mvp;
 
+/* Window rotation by id 0,1,2,3 (represents 0,90,180,270) */
+uniform int rotation_id;
+
 /* All except nomul */
 #ifndef SHD_NOMUL
 attribute vec4 color;
@@ -130,8 +133,13 @@ void main()
 #ifdef SHD_MASK
    // mask_coord.w contains the Y-invert flag
    // position on screen in [0..1] range of current pixel
-   vec4 mask_Position = mvp * vertex * vec4(0.5, sign(mask_coord.w) * 0.5, 0.5, 0.5) + vec4(0.5, 0.5, 0, 0);
-   tex_m = mask_Position.xy * abs(mask_coord.zw) + mask_coord.xy;
+   vec4 window_Position = mvp * vertex * vec4(0.5, sign(mask_coord.w) * 0.5, 0.5, 0.5) + vec4(0.5, 0.5, 0, 0);
+   vec2 pos[4];
+   pos[0] = vec2(window_Position.xy);
+   pos[1] = vec2(1.0 - window_Position.y, window_Position.x);
+   pos[2] = vec2(1.0 - window_Position.xy);
+   pos[3] = vec2(window_Position.y, 1.0 - window_Position.x);
+   tex_m = pos[rotation_id] * abs(mask_coord.zw) + mask_coord.xy;
 #endif
 }