Merge pull request #1440 from Sonicadvance1/attributeless-workaround

Implements PP shader system using attribute workaround.

1 files changed, 51 insertions, 2 deletions

diff --git a/Source/Core/VideoBackends/OGL/PostProcessing.cpp b/Source/Core/VideoBackends/OGL/PostProcessing.cpp
index f3017c326d..434a1d94a3 100644
--- a/Source/Core/VideoBackends/OGL/PostProcessing.cpp
+++ b/Source/Core/VideoBackends/OGL/PostProcessing.cpp
@@ -11,12 +11,22 @@
 #include "VideoBackends/OGL/PostProcessing.h"
 #include "VideoBackends/OGL/ProgramShaderCache.h"
 
+#include "VideoCommon/DriverDetails.h"
 #include "VideoCommon/VideoCommon.h"
 #include "VideoCommon/VideoConfig.h"
 
 namespace OGL
 {
 
+static char s_vertex_workaround_shader[] =
+	"in vec4 rawpos;\n"
+	"out vec2 uv0;\n"
+	"uniform vec4 src_rect;\n"
+	"void main(void) {\n"
+	"	gl_Position = vec4(rawpos.xy, 0.0, 1.0);\n"
+	"	uv0 = rawpos.zw * src_rect.zw + src_rect.xy;\n"
+	"}\n";
+
 static char s_vertex_shader[] =
 	"out vec2 uv0;\n"
 	"uniform vec4 src_rect;\n"
@@ -29,12 +39,26 @@ static char s_vertex_shader[] =
 OpenGLPostProcessing::OpenGLPostProcessing()
 {
 	CreateHeader();
+
+	m_attribute_workaround = DriverDetails::HasBug(DriverDetails::BUG_BROKENATTRIBUTELESS);
+	if (m_attribute_workaround)
+	{
+		glGenBuffers(1, &m_attribute_vbo);
+		glGenVertexArrays(1, &m_attribute_vao);
+	}
+
 	m_initialized = false;
 }
 
 OpenGLPostProcessing::~OpenGLPostProcessing()
 {
 	m_shader.Destroy();
+
+	if (m_attribute_workaround)
+	{
+		glDeleteBuffers(1, &m_attribute_vbo);
+		glDeleteVertexArrays(1, &m_attribute_vao);
+	}
 }
 
 void OpenGLPostProcessing::BlitFromTexture(TargetRectangle src, TargetRectangle dst,
@@ -46,6 +70,9 @@ void OpenGLPostProcessing::BlitFromTexture(TargetRectangle src, TargetRectangle
 
 	glViewport(dst.left, dst.bottom, dst.GetWidth(), dst.GetHeight());
 
+	if (m_attribute_workaround)
+		glBindVertexArray(m_attribute_vao);
+
 	m_shader.Bind();
 
 	glUniform4f(m_uniform_resolution, (float)src_width, (float)src_height, 1.0f / (float)src_width, 1.0f / (float)src_height);
@@ -150,13 +177,18 @@ void OpenGLPostProcessing::ApplyShader()
 
 	code = LoadShaderOptions(code);
 
+	const char* vertex_shader = s_vertex_shader;
+
+	if (m_attribute_workaround)
+		vertex_shader = s_vertex_workaround_shader;
+
 	// and compile it
-	if (!ProgramShaderCache::CompileShader(m_shader, s_vertex_shader, code.c_str()))
+	if (!ProgramShaderCache::CompileShader(m_shader, vertex_shader, code.c_str()))
 	{
 		ERROR_LOG(VIDEO, "Failed to compile post-processing shader %s", m_config.GetShader().c_str());
 
 		code = LoadShaderOptions(default_shader);
-		ProgramShaderCache::CompileShader(m_shader, s_vertex_shader, code.c_str());
+		ProgramShaderCache::CompileShader(m_shader, vertex_shader, code.c_str());
 	}
 
 	// read uniform locations
@@ -164,6 +196,23 @@ void OpenGLPostProcessing::ApplyShader()
 	m_uniform_time = glGetUniformLocation(m_shader.glprogid, "time");
 	m_uniform_src_rect = glGetUniformLocation(m_shader.glprogid, "src_rect");
 
+	if (m_attribute_workaround)
+	{
+		GLfloat vertices[] = {
+			-1.f, -1.f, 0.f, 0.f,
+			 1.f, -1.f, 1.f, 0.f,
+			-1.f,  1.f, 0.f, 1.f,
+			 1.f,  1.f, 1.f, 1.f,
+		};
+
+		glBindBuffer(GL_ARRAY_BUFFER, m_attribute_vbo);
+		glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
+
+		glBindVertexArray(m_attribute_vao);
+		glEnableVertexAttribArray(SHADER_POSITION_ATTRIB);
+		glVertexAttribPointer(SHADER_POSITION_ATTRIB, 4, GL_FLOAT, 0, 0, nullptr);
+	}
+
 	for (const auto& it : m_config.GetOptions())
 	{
 		std::string glsl_name = "option_" + it.first;