LibGL: Implement glColorMask

Author: https://github.com/Quaker762
Commit: https://github.com/SerenityOS/serenity/commit/8157e7740b1
Pull-request: https://github.com/SerenityOS/serenity/pull/9381
Reviewed-by: https://github.com/sunverwerth ✅

Userland/Libraries/LibGL/GL/gl.h

@@ -279,6 +279,7 @@ typedef float GLclampf;
 typedef double GLdouble;
 typedef unsigned int GLenum;
 typedef unsigned int GLbitfield;
+typedef unsigned char GLboolean;
 
 GLAPI void glBegin(GLenum mode);
 GLAPI void glClear(GLbitfield mask);
@@ -290,6 +291,7 @@ GLAPI void glColor4f(GLfloat r, GLfloat g, GLfloat b, GLfloat a);
 GLAPI void glColor4fv(const GLfloat* v);
 GLAPI void glColor4ub(GLubyte r, GLubyte g, GLubyte b, GLubyte a);
 GLAPI void glColor4ubv(const GLubyte* v);
+GLAPI void glColorMask(GLboolean red, GLboolean green, GLboolean blue, GLboolean alpha);
 GLAPI void glDeleteTextures(GLsizei n, const GLuint* textures);
 GLAPI void glEnd();
 GLAPI void glFrustum(GLdouble left, GLdouble right, GLdouble bottom, GLdouble top, GLdouble nearVal, GLdouble farVal);

Userland/Libraries/LibGL/GLContext.h

@@ -71,6 +71,7 @@ public:
     virtual void gl_tex_coord_pointer(GLint size, GLenum type, GLsizei stride, const void* pointer) = 0;
     virtual void gl_draw_arrays(GLenum mode, GLint first, GLsizei count) = 0;
     virtual void gl_draw_elements(GLenum mode, GLsizei count, GLenum type, const void* indices) = 0;
+    virtual void gl_color_mask(GLboolean red, GLboolean green, GLboolean blue, GLboolean alpha) = 0;
 
     virtual void present() = 0;
 };

Userland/Libraries/LibGL/GLUtils.cpp

@@ -45,6 +45,11 @@ void glClearDepth(GLdouble depth)
     g_gl_context->gl_clear_depth(depth);
 }
 
+void glColorMask(GLboolean red, GLboolean green, GLboolean blue, GLboolean alpha)
+{
+    g_gl_context->gl_color_mask(red, green, blue, alpha);
+}
+
 GLubyte* glGetString(GLenum name)
 {
     return g_gl_context->gl_get_string(name);

Userland/Libraries/LibGL/SoftwareGLContext.cpp

@@ -1694,6 +1694,35 @@ void SoftwareGLContext::read_from_vertex_attribute_pointer(VertexAttribPointer c
     }
 }
 
+void SoftwareGLContext::gl_color_mask(GLboolean red, GLboolean green, GLboolean blue, GLboolean alpha)
+{
+    auto options = m_rasterizer.options();
+    auto mask = options.color_mask;
+
+    if (!red)
+        mask &= ~0x000000ff;
+    else
+        mask |= 0x000000ff;
+
+    if (!green)
+        mask &= ~0x0000ff00;
+    else
+        mask |= 0x0000ff00;
+
+    if (!blue)
+        mask &= ~0x00ff0000;
+    else
+        mask |= 0x00ff0000;
+
+    if (!alpha)
+        mask &= ~0xff000000;
+    else
+        mask |= 0xff000000;
+
+    options.color_mask = mask;
+    m_rasterizer.set_options(options);
+}
+
 void SoftwareGLContext::present()
 {
     m_rasterizer.blit_to(*m_frontbuffer);

Userland/Libraries/LibGL/SoftwareGLContext.h

@@ -81,7 +81,7 @@ public:
     virtual void gl_tex_coord_pointer(GLint size, GLenum type, GLsizei stride, const void* pointer) override;
     virtual void gl_draw_arrays(GLenum mode, GLint first, GLsizei count) override;
     virtual void gl_draw_elements(GLenum mode, GLsizei count, GLenum type, const void* indices) override;
-
+    virtual void gl_color_mask(GLboolean red, GLboolean green, GLboolean blue, GLboolean alpha) override;
     virtual void present() override;
 
 private:

Userland/Libraries/LibGL/SoftwareRasterizer.cpp

@@ -383,7 +383,7 @@ static void rasterize_triangle(const RasterizerOptions& options, Gfx::Bitmap& re
                             + float_dst * dst_factor_dst_color
                             + FloatVector4(float_dst.w(), float_dst.w(), float_dst.w(), float_dst.w()) * dst_factor_dst_alpha;
 
-                        *dst = to_rgba32(*src * src_factor + float_dst * dst_factor);
+                        *dst = (*dst & ~options.color_mask) | (to_rgba32(*src * src_factor + float_dst * dst_factor) & options.color_mask);
                     }
                 }
             } else {
@@ -395,7 +395,7 @@ static void rasterize_triangle(const RasterizerOptions& options, Gfx::Bitmap& re
                         if (~pixel_mask[y] & (1 << x))
                             continue;
 
-                        *dst = to_rgba32(*src);
+                        *dst = (*dst & ~options.color_mask) | (to_rgba32(*src) & options.color_mask);
                     }
                 }
             }

Userland/Libraries/LibGL/SoftwareRasterizer.h

@@ -28,6 +28,7 @@ struct RasterizerOptions {
     bool enable_blending { false };
     GLenum blend_source_factor { GL_ONE };
     GLenum blend_destination_factor { GL_ONE };
+    u32 color_mask { 0xffffffff };
 };
 
 class SoftwareRasterizer final {