opengl: use MVP matrix in vertex shaders, pixel offsets

ChangChange all vertex shaders to accept model, view, projection
matrix to calculate the vertex position. So now we don't need to
convert the coordinates to OpenGL coordinate space [-1.0, 1.0]
anymore.

Additionally make it possible to offset vertex coordinates so
we can apply 0.5 px offset (to hit the pixel center) at some
operations.

Change-Id: I8e0a61d5fd4ab6aaa1c0c94439061725918577a0

1 files changed, 26 insertions, 4 deletions

diff --git a/vcl/opengl/program.cxx b/vcl/opengl/program.cxx
index d40aa30695f9..157243b746bc 100644
--- a/vcl/opengl/program.cxx
+++ b/vcl/opengl/program.cxx
@@ -13,6 +13,7 @@
 
 #include <glm/glm.hpp>
 #include <glm/gtc/type_ptr.hpp>
+#include <glm/gtc/matrix_transform.hpp>
 
 OpenGLProgram::OpenGLProgram() :
     mnId( 0 ),
@@ -238,6 +239,19 @@ void OpenGLProgram::SetTransform(
     glUniformMatrix4fv( nUniform, 1, GL_FALSE, glm::value_ptr( mMatrix ) );
 }
 
+void OpenGLProgram::ApplyMatrix(float fWidth, float fHeight, float fPixelOffset)
+{
+    OString sProjectionMatrix("mvp");
+    GLuint nUniform = GetUniformLocation(sProjectionMatrix);
+
+    glm::mat4 mMVP = glm::ortho(0.0f, fWidth, fHeight, 0.0f, 0.0f, 1.0f);
+
+    if (fPixelOffset != 0.0f)
+        mMVP = glm::translate(mMVP, glm::vec3(fPixelOffset, fPixelOffset, 0.0f));
+
+    glUniformMatrix4fv(nUniform, 1, GL_FALSE, glm::value_ptr(mMVP));
+}
+
 void OpenGLProgram::SetBlendMode( GLenum nSFactor, GLenum nDFactor )
 {
     glEnable( GL_BLEND );
@@ -247,12 +261,20 @@ void OpenGLProgram::SetBlendMode( GLenum nSFactor, GLenum nDFactor )
 
 bool OpenGLProgram::DrawTexture( OpenGLTexture& rTexture )
 {
-    GLfloat aPosition[8] = { -1, -1, -1, 1, 1, 1, 1, -1 };
-    GLfloat aTexCoord[8];
-
-    if( !rTexture )
+    if (!rTexture)
         return false;
 
+    float fWidth = rTexture.GetWidth();
+    float fHeight = rTexture.GetHeight();
+
+    float fMinX = 0.0f;
+    float fMaxX = fWidth;
+    float fMinY = 0.0f;
+    float fMaxY = fHeight;
+
+    GLfloat aPosition[8] = { fMinX, fMaxY, fMinX, fMinY, fMaxX, fMinY, fMaxX, fMaxY };
+    GLfloat aTexCoord[8];
+
     rTexture.GetWholeCoord( aTexCoord );
     SetVertices( aPosition );
     SetTextureCoord( aTexCoord );