Improved render to texture

Support render texture size different than screen size

4 files changed, 49 insertions, 9 deletions

diff --git a/src/core.c b/src/core.c
index a94ad48d..08f9a7e2 100644
--- a/src/core.c
+++ b/src/core.c
@@ -562,9 +562,8 @@ void Begin2dMode(Camera2D camera)
     Matrix matOrigin = MatrixTranslate(-camera.target.x, -camera.target.y, 0.0f);
     Matrix matRotation = MatrixRotate((Vector3){ 0.0f, 0.0f, 1.0f }, camera.rotation*DEG2RAD);
     Matrix matScale = MatrixScale(camera.zoom, camera.zoom, 1.0f);
-    
     Matrix matTranslation = MatrixTranslate(camera.offset.x + camera.target.x, camera.offset.y + camera.target.y, 0.0f);
-
+    
     Matrix matTransform = MatrixMultiply(MatrixMultiply(matOrigin, MatrixMultiply(matScale, matRotation)), matTranslation);
     
     rlMultMatrixf(MatrixToFloat(matTransform));
@@ -627,11 +626,24 @@ void BeginTextureMode(RenderTexture2D target)
 {
     rlglDraw();                         // Draw Buffers (Only OpenGL 3+ and ES2)
 
-    rlEnableRenderTexture(target.id);
-    
+    rlEnableRenderTexture(target.id);   // Enable render target
+
     rlClearScreenBuffers();             // Clear render texture buffers
+    
+    // Set viewport to framebuffer size
+    rlViewport(0, 0, target.texture.width, target.texture.height); 
+    
+    rlMatrixMode(RL_PROJECTION);        // Switch to PROJECTION matrix
+    rlLoadIdentity();                   // Reset current matrix (PROJECTION)
 
+    // Set orthographic projection to current framebuffer size
+    // NOTE: Configured top-left corner as (0, 0)
+    rlOrtho(0, target.texture.width, target.texture.height, 0, 0.0f, 1.0f);        
+
+    rlMatrixMode(RL_MODELVIEW);         // Switch back to MODELVIEW matrix
     rlLoadIdentity();                   // Reset current matrix (MODELVIEW)
+
+    //rlScalef(0.0f, -1.0f, 0.0f);      // Flip Y-drawing (?)
 }
 
 // Ends drawing to render texture
@@ -639,7 +651,21 @@ void EndTextureMode(void)
 {
     rlglDraw();                         // Draw Buffers (Only OpenGL 3+ and ES2)
 
-    rlDisableRenderTexture();
+    rlDisableRenderTexture();           // Disable render target
+
+    // Set viewport to default framebuffer size (screen size)
+    // TODO: consider possible viewport offsets
+    rlViewport(0, 0, GetScreenWidth(), GetScreenHeight());
+    
+    rlMatrixMode(RL_PROJECTION);        // Switch to PROJECTION matrix
+    rlLoadIdentity();                   // Reset current matrix (PROJECTION)
+    
+    // Set orthographic projection to current framebuffer size
+    // NOTE: Configured top-left corner as (0, 0)
+    rlOrtho(0, GetScreenWidth(), GetScreenHeight(), 0, 0.0f, 1.0f);
+
+    rlMatrixMode(RL_MODELVIEW);         // Switch back to MODELVIEW matrix
+    rlLoadIdentity();                   // Reset current matrix (MODELVIEW)
 }
 
 // Set target FPS for the game
diff --git a/src/rlgl.c b/src/rlgl.c
index d319119f..cc4c4c2f 100644
--- a/src/rlgl.c
+++ b/src/rlgl.c
@@ -404,6 +404,12 @@ void rlOrtho(double left, double right, double bottom, double top, double near,
 
 #endif
 
+// Set the viewport area (trasnformation from normalized device coordinates to window coordinates)
+void rlViewport(int x, int y, int width, int height)
+{
+    glViewport(x, y, width, height);
+}
+
 //----------------------------------------------------------------------------------
 // Module Functions Definition - Vertex level operations
 //----------------------------------------------------------------------------------
@@ -725,17 +731,25 @@ void rlDisableTexture(void)
 #endif
 }
 
+// Enable rendering to texture (fbo)
 void rlEnableRenderTexture(unsigned int id)
 {
 #if defined(GRAPHICS_API_OPENGL_33) || defined(GRAPHICS_API_OPENGL_ES2)
     glBindFramebuffer(GL_FRAMEBUFFER, id);
+
+    //glDisable(GL_CULL_FACE);    // Allow double side drawing for texture flipping
+    //glCullFace(GL_FRONT);
 #endif
 }
 
+// Disable rendering to texture
 void rlDisableRenderTexture(void)
 {
 #if defined(GRAPHICS_API_OPENGL_33) || defined(GRAPHICS_API_OPENGL_ES2)
     glBindFramebuffer(GL_FRAMEBUFFER, 0);
+
+    //glEnable(GL_CULL_FACE);
+    //glCullFace(GL_BACK);
 #endif
 }
 
diff --git a/src/rlgl.h b/src/rlgl.h
index fa35dbc6..a3ba6cd5 100644
--- a/src/rlgl.h
+++ b/src/rlgl.h
@@ -247,6 +247,7 @@ void rlScalef(float x, float y, float z);       // Multiply the current matrix b
 void rlMultMatrixf(float *mat);                 // Multiply the current matrix by another matrix
 void rlFrustum(double left, double right, double bottom, double top, double near, double far);
 void rlOrtho(double left, double right, double bottom, double top, double near, double far);
+void rlViewport(int x, int y, int width, int height); // Set the viewport area
 
 //------------------------------------------------------------------------------------
 // Functions Declaration - Vertex level operations
diff --git a/src/textures.c b/src/textures.c
index 79047ab7..439311f6 100644
--- a/src/textures.c
+++ b/src/textures.c
@@ -1385,10 +1385,6 @@ void DrawTextureEx(Texture2D texture, Vector2 position, float rotation, float sc
 void DrawTextureRec(Texture2D texture, Rectangle sourceRec, Vector2 position, Color tint)
 {
     Rectangle destRec = { (int)position.x, (int)position.y, abs(sourceRec.width), abs(sourceRec.height) };
-    
-    if (sourceRec.width < 0) sourceRec.x -= sourceRec.width;
-    if (sourceRec.height < 0) sourceRec.y -= sourceRec.height;
-    
     Vector2 origin = { 0, 0 };
 
     DrawTexturePro(texture, sourceRec, destRec, origin, 0.0f, tint);
@@ -1398,6 +1394,9 @@ void DrawTextureRec(Texture2D texture, Rectangle sourceRec, Vector2 position, Co
 // NOTE: origin is relative to destination rectangle size
 void DrawTexturePro(Texture2D texture, Rectangle sourceRec, Rectangle destRec, Vector2 origin, float rotation, Color tint)
 {
+    if (sourceRec.width < 0) sourceRec.x -= sourceRec.width;
+    if (sourceRec.height < 0) sourceRec.y -= sourceRec.height;
+    
     rlEnableTexture(texture.id);
 
     rlPushMatrix();