OpenGL: tweak image shaders & code that uses them

- rename image shaders to describe exactly what they do
- rename inputs to match other built-in shaders
- set & use active texture unit
- no need to enable/disable textures with GLSL
- pull vertex format setup out of loops

1 files changed, 18 insertions, 0 deletions

diff --git a/source/blender/gpu/shaders/gpu_shader_image_modulate_alpha_frag.glsl b/source/blender/gpu/shaders/gpu_shader_image_modulate_alpha_frag.glsl
new file mode 100644
index 00000000000..74e17198985
--- /dev/null
+++ b/source/blender/gpu/shaders/gpu_shader_image_modulate_alpha_frag.glsl
@@ -0,0 +1,18 @@
+
+#if __VERSION__ == 120
+  varying vec2 texCoord_interp;
+  #define fragColor gl_FragColor
+#else
+  in vec2 texCoord_interp;
+  out vec4 fragColor;
+  #define texture2D texture
+#endif
+
+uniform float alpha;
+uniform sampler2D image;
+
+void main()
+{
+	fragColor = texture2D(image, texCoord_interp);
+	fragColor.a *= alpha;
+}