Added loading of a TGA mask image to generate alpha canal

src/Texture.cpp

@@ -76,5 +76,44 @@ bool Texture::load_rgb_tga(const std::string& rgb_filename)
 
 bool Texture::load_rgba_tga(const std::string& rgb_filename, const std::string& mask_filename)
 {
+    uint8_t* rgb_data = nullptr;
+    uint8_t* mask_data = nullptr;
+
+    bool load_successful = true;
+    // Load rgb and alpha data before merging them
+    load_successful &= load_tga(rgb_filename, rgb_data);
+    uint16_t temp_width = width;
+    uint16_t temp_height = height;
+
+    load_successful &= load_tga(mask_filename, mask_data);
+
+    if (!load_successful)
+    {
+        std::cerr << "Error while loading RGBA image" << std::endl;
         return false;
     }
+    if (temp_width != width || temp_height != height)
+    {
+        std::cerr << "Error while loading RGBA image : image and mask dimensions do no match : " << std::endl;
+        std::cerr << temp_width << "x" << temp_height << " versus " << width << "x" << height << std::endl;
+        return false;
+    }
+
+
+    image_data = new uint8_t[width*height*4];
+
+    // Merge the two images
+    for(int i = 0;i<height*width;i++)
+    {
+        for(int j = 0;j<3;j++)
+        {
+            image_data[i*4+j] = rgb_data[i*3+j];
+        }
+        image_data[i*4+3] = mask_data[i*3];
+    }
+
+    // Now we have an RGBA image, update color_bits
+    color_bits = 32;
+
+    return true;
+}

src/Texture.h

@@ -26,7 +26,7 @@ public:
 
     /// Load an RGB image from an RGB TGA file
     bool load_rgb_tga(const std::string& rgb_filename);
-    /// Load an RGBA image from an rgb and an alpha tga file
+    /// Load an RGBA image from an rgb and an alpha (Greyscale) tga file
     bool load_rgba_tga(const std::string& rgb_filename,const std::string& mask_filename);
 
 private:

src/displayers.cpp

@@ -62,6 +62,8 @@ void display_rotating_pyramid(float x, float y, float z, float c, float h, float
 
 void display_tree(float x, float y, float z, float h, float w, const Texture& tree_texture)
 {
+    glEnable(GL_ALPHA_TEST);
+
     glPolygonMode(GL_FRONT_AND_BACK,GL_FILL);
     glBindTexture(GL_TEXTURE_2D,tree_texture.opengl_id[0]);
 
@@ -95,4 +97,6 @@ void display_tree(float x, float y, float z, float h, float w, const Texture& tr
     glVertex3f(x,y+h,z+w/2);
 
     glEnd();
+
+    glDisable(GL_ALPHA_TEST);
 }

src/main.cpp

@@ -56,7 +56,6 @@ int main(int argc, char** argv)
 
     // Setup OPenGL to use textures
     glEnable(GL_TEXTURE_2D);
-    glEnable(GL_ALPHA_TEST);
     glAlphaFunc(GL_GREATER, 0.5);
 
     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER,GL_NEAREST);
@@ -66,11 +65,10 @@ int main(int argc, char** argv)
     glTexEnvi(GL_TEXTURE_2D, GL_TEXTURE_ENV_MODE, GL_MODULATE);
 
     // Load and generate tree texture
-    tree_texture.load_rgb_tga("resources/arbre.tga");
+    tree_texture.load_rgba_tga("resources/arbre.tga","resources/arbre_masque.tga");
     glGenTextures(1,tree_texture.opengl_id);
     glBindTexture(GL_TEXTURE_2D,tree_texture.opengl_id[0]);
-    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB8, tree_texture.width,tree_texture.height,0,GL_RGB,GL_UNSIGNED_BYTE,tree_texture.image_data);
-    gluBuild2DMipmaps(GL_TEXTURE_2D,GL_RGB8,tree_texture.width,tree_texture.height,GL_RGB,GL_UNSIGNED_BYTE,tree_texture.image_data);
+    gluBuild2DMipmaps(GL_TEXTURE_2D,GL_RGBA8,tree_texture.width,tree_texture.height,GL_RGBA,GL_UNSIGNED_BYTE,tree_texture.image_data);
 
     glViewport(0,0,glutGet(GLUT_WINDOW_WIDTH),glutGet(GLUT_WINDOW_HEIGHT));