Switch to use a single triangle when drawing screen quads for a slight cache locality improvement

src/common/rendering/gl/gl_postprocess.cpp

@@ -49,7 +49,7 @@ void FGLRenderer::RenderScreenQuad()
 {
 	auto buffer = static_cast<GLVertexBuffer *>(screen->mVertexData->GetBufferObjects().first);
 	buffer->Bind(nullptr);
-	glDrawArrays(GL_TRIANGLE_STRIP, FFlatVertexBuffer::PRESENT_INDEX, 4);
+	glDrawArrays(GL_TRIANGLE_STRIP, FFlatVertexBuffer::PRESENT_INDEX, 3);
 }
 
 void FGLRenderer::PostProcessScene(int fixedcm, float flash, const std::function<void()> &afterBloomDrawEndScene2D)

src/common/rendering/hwrenderer/data/flatvertices.cpp

@@ -63,9 +63,9 @@ FFlatVertexBuffer::FFlatVertexBuffer(int width, int height)
 
 	// and this is for the postprocessing copy operation
 	vbo_shadowdata[8].Set(-1.0f, -1.0f, 0, 0.0f, 0.0f);
-	vbo_shadowdata[9].Set(-1.0f, 1.0f, 0, 0.0f, 1.f);
-	vbo_shadowdata[10].Set(1.0f, -1.0f, 0, 1.f, 0.0f);
-	vbo_shadowdata[11].Set(1.0f, 1.0f, 0, 1.f, 1.f);
+	vbo_shadowdata[9].Set(3.0f, -1.0f, 0, 2.f, 0.0f);
+	vbo_shadowdata[10].Set(-1.0f, 3.0f, 0, 0.0f, 2.f);
+	vbo_shadowdata[11].Set(3.0f, 3.0f, 0, 2.f, 2.f); // Note: not used anymore
 
 	// The next two are the stencil caps.
 	vbo_shadowdata[12].Set(-32767.0f, 32767.0f, -32767.0f, 0, 0);

src/common/rendering/vulkan/renderer/vk_postprocess.cpp

@@ -565,7 +565,7 @@ void VkPPRenderState::RenderScreenQuad(VkPPRenderPassSetup *passSetup, VulkanDes
 		cmdbuffer->setStencilReference(VK_STENCIL_FRONT_AND_BACK, screen->stencilValue);
 	if (pushConstantsSize > 0)
 		cmdbuffer->pushConstants(passSetup->PipelineLayout.get(), VK_SHADER_STAGE_FRAGMENT_BIT, 0, pushConstantsSize, pushConstants);
-	cmdbuffer->draw(4, 1, FFlatVertexBuffer::PRESENT_INDEX, 0);
+	cmdbuffer->draw(3, 1, FFlatVertexBuffer::PRESENT_INDEX, 0);
 	cmdbuffer->endRenderPass();
 }