no need to compile a shader for multiplying alpha

rendering/renderfunctions.cpp

@@ -367,11 +367,11 @@ GLuint compose_sequence(ComposeSequenceParams &params) {
 
               if (!c->media()->to_footage()->alpha_is_premultiplied) {
                 // alpha is not premultiplied, we'll need to multiply it for the rest of the pipeline
-                params.premultiply_program->bind();
+                params.ctx->functions()->glBlendFuncSeparate(GL_SRC_ALPHA, GL_ZERO, GL_ONE, GL_ZERO);
 
                 textureID = draw_clip(c->fbo[0], textureID, true);
 
-                params.premultiply_program->release();
+                glBlendFunc(GL_ONE, GL_ONE_MINUS_SRC_ALPHA);
 
                 fbo_switcher = true;
               }

rendering/renderfunctions.h

@@ -143,18 +143,6 @@ struct ComposeSequenceParams {
     */
   QOpenGLShaderProgram* blend_mode_program;
 
-  /**
-    * @brief Premultiply alpha shader
-    *
-    * Used only for video rendering. Never accessed with audio rendering.
-    *
-    * compose_sequence()'s internal composition
-    * expects premultipled alpha, but it will pre-emptively multiply any footage that is not set as already
-    * premultiplied (see Footage::alpha_is_premultiplied) using this shader. Must be compiled and linked beforehand.
-    * See RenderThread::premultiply_program for how this is properly set up.
-    */
-  QOpenGLShaderProgram* premultiply_program;
-
   /**
     * @brief The OpenGL framebuffer object that the final texture to be shown is rendered to.
     *

rendering/renderthread.cpp

@@ -39,7 +39,6 @@ RenderThread::RenderThread() :
   share_ctx(nullptr),
   ctx(nullptr),
   blend_mode_program(nullptr),
-  premultiply_program(nullptr),
   seq(nullptr),
   tex_width(-1),
   tex_height(-1),
@@ -104,11 +103,6 @@ void RenderThread::run() {
           blend_mode_program->addShaderFromSourceCode(QOpenGLShader::Fragment, olive::generated_blending_shader);
           olive::effects_loaded.unlock();
           blend_mode_program->link();
-
-          premultiply_program = new QOpenGLShaderProgram();
-          premultiply_program->addShaderFromSourceFile(QOpenGLShader::Vertex, ":/internalshaders/common.vert");
-          premultiply_program->addShaderFromSourceFile(QOpenGLShader::Fragment, ":/internalshaders/premultiply.frag");
-          premultiply_program->link();
         }
 
         // draw frame
@@ -153,7 +147,6 @@ void RenderThread::paint() {
   params.wait_for_mutexes = true;
   params.playback_speed = 1;
   params.blend_mode_program = blend_mode_program;
-  params.premultiply_program = premultiply_program;
   params.backend_buffer1 = back_buffer_1.buffer();
   params.backend_buffer2 = back_buffer_2.buffer();
   params.backend_attachment1 = back_buffer_1.texture();
@@ -280,9 +273,6 @@ void RenderThread::delete_buffers() {
 void RenderThread::delete_shaders() {
   delete blend_mode_program;
   blend_mode_program = nullptr;
-
-  delete premultiply_program;
-  premultiply_program = nullptr;
 }
 
 void RenderThread::delete_ctx() {

rendering/renderthread.h

@@ -92,7 +92,6 @@ private:
   QOpenGLContext* share_ctx;
   QOpenGLContext* ctx;
   QOpenGLShaderProgram* blend_mode_program;
-  QOpenGLShaderProgram* premultiply_program;
 
   FramebufferObject back_buffer_1;
   FramebufferObject back_buffer_2;