LibGL: Implement glFogfv

This currently just sets the fog colour in the rasterizer.

Userland/Libraries/LibGL/CMakeLists.txt

@@ -7,6 +7,7 @@ set(SOURCES
     GLBlend.cpp
     GLColor.cpp
     GLContext.cpp
+    GLFog.cpp
     GLLights.cpp
     GLLists.cpp
     GLMat.cpp

Userland/Libraries/LibGL/GL/gl.h

@@ -374,6 +374,7 @@ GLAPI void glDrawElements(GLenum mode, GLsizei count, GLenum type, const void* i
 GLAPI void glDepthRange(GLdouble nearVal, GLdouble farVal);
 GLAPI void glDepthFunc(GLenum func);
 GLAPI void glPolygonMode(GLenum face, GLenum mode);
+GLAPI void glFogfv(GLenum mode, GLfloat* params);
 
 #ifdef __cplusplus
 }

Userland/Libraries/LibGL/GLContext.h

@@ -77,6 +77,7 @@ public:
     virtual void gl_depth_range(GLdouble min, GLdouble max) = 0;
     virtual void gl_depth_func(GLenum func) = 0;
     virtual void gl_polygon_mode(GLenum face, GLenum mode) = 0;
+    virtual void gl_fogfv(GLenum pname, GLfloat* params) = 0;
 
     virtual void present() = 0;
 };

Userland/Libraries/LibGL/GLFog.cpp

@@ -0,0 +1,15 @@
+/*
+ * Copyright (c) 2021, Jesse Buhagiar <jooster669@gmail.com>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include "GL/gl.h"
+#include "GLContext.h"
+
+extern GL::GLContext* g_gl_context;
+
+void glFogfv(GLenum pname, GLfloat* params)
+{
+    g_gl_context->gl_fogfv(pname, params);
+}

Userland/Libraries/LibGL/SoftwareGLContext.cpp

@@ -1745,6 +1745,26 @@ void SoftwareGLContext::gl_polygon_mode(GLenum face, GLenum mode)
     m_rasterizer.set_options(options);
 }
 
+void SoftwareGLContext::gl_fogfv(GLenum pname, GLfloat* params)
+{
+    RETURN_WITH_ERROR_IF(m_in_draw_state, GL_INVALID_OPERATION);
+
+    auto options = m_rasterizer.options();
+
+    switch (pname) {
+    case GL_FOG_COLOR:
+        // Set rasterizer options fog color
+        // NOTE: We purposefully don't check for `nullptr` here (as with other calls). The spec states nothing
+        // about us checking for such things. If the programmer does so and hits SIGSEGV, that's on them.
+        options.fog_color = FloatVector4 { params[0], params[1], params[2], params[3] };
+        break;
+    default:
+        RETURN_WITH_ERROR_IF(true, GL_INVALID_ENUM);
+    }
+
+    m_rasterizer.set_options(options);
+}
+
 void SoftwareGLContext::present()
 {
     m_rasterizer.blit_to(*m_frontbuffer);

Userland/Libraries/LibGL/SoftwareGLContext.h

@@ -87,6 +87,7 @@ public:
     virtual void gl_depth_range(GLdouble min, GLdouble max) override;
     virtual void gl_depth_func(GLenum func) override;
     virtual void gl_polygon_mode(GLenum face, GLenum mode) override;
+    virtual void gl_fogfv(GLenum pname, GLfloat* params) override;
     virtual void present() override;
 
 private:

Userland/Libraries/LibGL/SoftwareRasterizer.h

@@ -33,6 +33,12 @@ struct RasterizerOptions {
     float depth_max { 1 };
     GLenum depth_func { GL_LESS };
     GLenum polygon_mode { GL_FILL };
+    FloatVector4 fog_color {
+        0.0f,
+        0.0f,
+        0.0f,
+        0.0f,
+    };
 };
 
 class SoftwareRasterizer final {