Blit single pixel onto target RenderTarget (cave-game)

include/JGL/types/RenderTarget.h

@@ -40,6 +40,12 @@ public:
 
     /// Blit a render target onto another. Will break if they're not the same size.
     static void Blit(const RenderTarget& source, RenderTarget* destination);
+
+    /// Blit a single pixel onto a Render Target.
+    /// @param color The color to render.
+    /// @param position The position in the destination to draw the pixel.
+    /// @param destination The destination RenderTarget.
+    static void Blit(const Color4& color, const Vector2& position, RenderTarget* destination);
     [[nodiscard]] bool TextureCreatedByRenderTarget() const;
 public:
     [[nodiscard]] Vector2 GetDimensions() const;

main.cpp

@@ -132,6 +132,7 @@ public:
     float fov = 90;
     float sprite_radians = 0;
     bool fov_increasing = true;
+    int blit_pos = 0;
 
     void display() {
 
@@ -195,7 +196,7 @@ public:
             J2D::DrawGradientLine(Colors::Red, Colors::Blue, {105, 375}, {200, 275}, 2);
             auto result = Jupiteroid.MeasureString("Jupiteroid Font", 16);
 
-            J2D::FillRect(Colors::Gray, {0, 0}, result);
+            //J2D::FillRect(Colors::Gray, {0, 0}, result);
             J2D::DrawString(Colors::Green, "Jupteroid Font", 0.f, 0, 1.f, 16, Jupiteroid);
             J2D::DrawString(Colors::White, "Position: " + std::to_string(camera->position.x) + " " + std::to_string(camera->position.y) + " " + std::to_string(camera->position.z), 0, 16, 1,16, Jupiteroid);
             J2D::DrawString(Colors::White, "ViewAngle: " + std::to_string(camera->angle.x) + " " + std::to_string(camera->angle.y) + " " + std::to_string(camera->angle.z), 0, 33, 1,16, Jupiteroid);
@@ -215,6 +216,7 @@ public:
             c.Draw();
             d.Draw();
         J2D::End();
+        RenderTarget::Blit(Colors::Red, {0, 0}, j2d_render_target);
 
         //Draw the Render Target that we just drew all that stuff onto.
 

src/types/RenderTarget.cpp

@@ -331,6 +331,40 @@ void JGL::RenderTarget::Blit(const JGL::RenderTarget& source, JGL::RenderTarget*
     glBindFramebuffer(GL_FRAMEBUFFER, current_fbo);
 }
 
+void JGL::RenderTarget::Blit(const Color4& color, const Vector2& position, JGL::RenderTarget* destination) {
+    if (position.x > destination->size.x || position.y > destination->size.y)
+        Logger::Warning("Blitting outside of the renderable area of the destination.");
+
+    Texture texture(Vector2(1,1));
+    RenderTarget source(&texture,color);
+
+    GLint current_draw_fbo = 0;
+    GLint current_read_fbo = 0;
+    GLint viewport[4];
+    GLfloat clear_color[4];
+    GLuint current_fbo = GetActiveGLFramebufferHandle();
+    glGetIntegerv(GL_VIEWPORT, viewport);
+    glGetFloatv(GL_COLOR_CLEAR_VALUE, clear_color);
+    glGetIntegerv(GL_READ_FRAMEBUFFER_BINDING, &current_read_fbo);
+    glGetIntegerv(GL_DRAW_FRAMEBUFFER_BINDING, &current_draw_fbo);
+
+    SetActiveGLRenderTarget(source);
+    glClearColor(color.RedChannelNormalized(), color.GreenChannelNormalized(), color.BlueChannelNormalized(), color.AlphaChannelNormalized());
+    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+
+    // Invert so it's relative to the top left corner.
+    int target_y = destination->size.y - position.y - 1;
+    glBindFramebuffer(GL_READ_FRAMEBUFFER, source.framebuffer_object);
+    glBindFramebuffer(GL_DRAW_FRAMEBUFFER, destination->framebuffer_object);
+    glBlitFramebuffer(0, 0, 1, 1, position.x, target_y, position.x + 1, target_y + 1, GL_COLOR_BUFFER_BIT, GL_NEAREST);
+
+    glBindFramebuffer(GL_READ_FRAMEBUFFER, current_read_fbo);
+    glBindFramebuffer(GL_DRAW_FRAMEBUFFER, current_draw_fbo);
+    glBindFramebuffer(GL_FRAMEBUFFER, current_fbo);
+    glViewport(viewport[0], viewport[1], viewport[2], viewport[3]);
+    glClearColor(clear_color[0], clear_color[1], clear_color[2], clear_color[3]);
+}
+
 JGL::RenderTarget::RenderTarget(const JGL::RenderTarget& rhs) {
     auto* this_render_target = new RenderTarget(rhs.size, rhs.clear_color, rhs.using_depth, rhs.msaa_sample_rate);
     RenderTarget::Blit(rhs, this_render_target);