LibGL: Turn Sampler2D into an actual class

This extracts the sampler functionality into its own class.
Beginning with OpenGL 3 samplers are actual objects, separate
from textures. It makes sense to do this already as it also
cleans up code organization quite a bit.

Userland/Libraries/LibGL/CMakeLists.txt

@@ -1,5 +1,6 @@
 set(SOURCES
     Tex/NameAllocator.cpp
+    Tex/Sampler2D.cpp
     Tex/Texture2D.cpp
     Tex/TextureUnit.cpp
     Clipper.cpp

Userland/Libraries/LibGL/SoftwareRasterizer.cpp

@@ -435,7 +435,7 @@ void SoftwareRasterizer::submit_triangle(const GLTriangle& triangle, const Array
                 continue;
 
             // FIXME: Don't assume Texture2D, _and_ work out how we blend/do multitexturing properly.....
-            texel = texel * static_ptr_cast<Texture2D>(texture_unit.bound_texture())->sample_texel(uv);
+            texel = texel * static_ptr_cast<Texture2D>(texture_unit.bound_texture())->sampler().sample(uv);
         }
 
         return texel;

Userland/Libraries/LibGL/Tex/MipMap.h

@@ -0,0 +1,49 @@
+/*
+ * Copyright (c) 2021, Jesse Buhagiar <jooster669@gmail.com>
+ * Copyright (c) 2021, Stephan Unverwerth <s.unverwerth@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/Vector.h>
+#include <LibGL/GL/gl.h>
+#include <LibGfx/Vector4.h>
+
+namespace GL {
+
+class MipMap {
+public:
+    MipMap() = default;
+    ~MipMap() = default;
+
+    void set_width(GLsizei width) { m_width = width; }
+    void set_height(GLsizei height) { m_height = height; }
+    GLsizei width() const { return m_width; }
+    GLsizei height() const { return m_height; }
+
+    Vector<u32>& pixel_data() { return m_pixel_data; }
+    const Vector<u32>& pixel_data() const { return m_pixel_data; }
+
+    FloatVector4 texel(unsigned x, unsigned y) const
+    {
+        if (x >= (unsigned)m_width || y >= (unsigned)m_height)
+            return { 0, 0, 0, 0 };
+
+        u32 texel = m_pixel_data.at(y * m_width + x);
+
+        return {
+            (texel & 0xff) / 255.f,
+            ((texel >> 8) & 0xff) / 255.f,
+            ((texel >> 16) & 0xff) / 255.f,
+            ((texel >> 24) & 0xff) / 255.f
+        };
+    }
+
+private:
+    GLsizei m_width;
+    GLsizei m_height;
+    Vector<u32> m_pixel_data;
+};
+}

Userland/Libraries/LibGL/Tex/Sampler2D.cpp

@@ -0,0 +1,53 @@
+/*
+ * Copyright (c) 2021, Stephan Unverwerth <s.unverwerth@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include "Sampler2D.h"
+
+#include <LibGL/Tex/Texture2D.h>
+#include <math.h>
+
+namespace GL {
+
+static constexpr float wrap_repeat(float value)
+{
+    return value - floorf(value);
+}
+
+FloatVector4 Sampler2D::sample(FloatVector2 const& uv) const
+{
+    // FIXME: Calculate the correct mipmap level here, need to receive uv derivatives for that
+    unsigned lod = 0;
+
+    MipMap const& mip = m_texture.mipmap(lod);
+
+    float x = uv.x();
+    float y = uv.y();
+
+    switch (m_wrap_s_mode) {
+    case GL_REPEAT:
+        x = wrap_repeat(x);
+        break;
+
+    default:
+        VERIFY_NOT_REACHED();
+    }
+
+    switch (m_wrap_t_mode) {
+    case GL_REPEAT:
+        y = wrap_repeat(y);
+        break;
+
+    default:
+        VERIFY_NOT_REACHED();
+    }
+
+    x *= mip.width() - 1;
+    y *= mip.height() - 1;
+
+    return mip.texel(static_cast<unsigned>(x), static_cast<unsigned>(y));
+}
+
+}

Userland/Libraries/LibGL/Tex/Sampler2D.h

@@ -0,0 +1,44 @@
+/*
+ * Copyright (c) 2021, Stephan Unverwerth <s.unverwerth@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <LibGL/GL/gl.h>
+#include <LibGfx/Vector2.h>
+#include <LibGfx/Vector4.h>
+
+namespace GL {
+
+class Texture2D;
+
+class Sampler2D final {
+public:
+    Sampler2D(Texture2D const& texture)
+        : m_texture(texture)
+    {
+    }
+
+    GLint min_filter() const { return m_min_filter; }
+    GLint mag_filter() const { return m_mag_filter; }
+    GLint wrap_s_mode() const { return m_wrap_s_mode; }
+    GLint wrap_t_mode() const { return m_wrap_t_mode; }
+
+    void set_min_filter(GLint value) { m_min_filter = value; }
+    void set_mag_filter(GLint value) { m_mag_filter = value; }
+    void set_wrap_s_mode(GLint value) { m_wrap_s_mode = value; }
+    void set_wrap_t_mode(GLint value) { m_wrap_t_mode = value; }
+
+    FloatVector4 sample(FloatVector2 const& uv) const;
+
+private:
+    Texture2D const& m_texture;
+
+    GLint m_min_filter { GL_NEAREST_MIPMAP_LINEAR };
+    GLint m_mag_filter { GL_LINEAR };
+    GLint m_wrap_s_mode { GL_REPEAT };
+    GLint m_wrap_t_mode { GL_REPEAT };
+};
+}

Userland/Libraries/LibGL/Tex/Texture2D.cpp

@@ -1,5 +1,6 @@
 /*
  * Copyright (c) 2021, Jesse Buhagiar <jooster669@gmail.com>
+ * Copyright (c) 2021, Stephan Unverwerth <s.unverwerth@serenityos.org>
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
@@ -112,24 +113,12 @@ void Texture2D::upload_texture_data(GLenum, GLint lod, GLint internal_format, GL
     mip.set_height(height);
 }
 
-FloatVector4 Texture2D::sample_texel(const FloatVector2& uv) const
+MipMap const& Texture2D::mipmap(unsigned lod) const
 {
-    auto& mip = m_mipmaps.at(0);
+    if (lod >= m_mipmaps.size())
+        return m_mipmaps.at(m_mipmaps.size() - 1);
 
-    // FIXME: Remove this to prevent a crash when we have proper texture binding
-    if (mip.width() == 0 || mip.height() == 0)
-        return { 1.0f, 1.0f, 1.0f, 1.0f };
-
-    u32 u = static_cast<u32>(uv.x() * mip.width());
-    u32 v = static_cast<u32>(uv.y() * mip.height());
-
-    u32 pixel = mip.pixel_data().at(v * mip.width() + u);
-
-    float b0 = ((pixel)&0xff) / 255.0f;
-    float b1 = ((pixel >> 8) & 0xff) / 255.0f;
-    float b2 = ((pixel >> 16) & 0xff) / 255.0f;
-
-    return { b0, b1, b2, 1.0f };
+    return m_mipmaps.at(lod);
 }
 
 }

Userland/Libraries/LibGL/Tex/Texture2D.h

@@ -1,5 +1,6 @@
 /*
  * Copyright (c) 2021, Jesse Buhagiar <jooster669@gmail.com>
+ * Copyright (c) 2021, Stephan Unverwerth <s.unverwerth@serenityos.org>
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
@@ -12,6 +13,8 @@
 #include <AK/RefCounted.h>
 #include <AK/Vector.h>
 #include <LibGL/GL/gl.h>
+#include <LibGL/Tex/MipMap.h>
+#include <LibGL/Tex/Sampler2D.h>
 #include <LibGfx/Vector2.h>
 #include <LibGfx/Vector4.h>
 
@@ -23,46 +26,22 @@ public:
     static constexpr u16 MAX_TEXTURE_SIZE = 2048;
     static constexpr u8 LOG2_MAX_TEXTURE_SIZE = 11;
 
-    class MipMap {
-    public:
-        MipMap() = default;
-        ~MipMap() = default;
-
-        void set_width(GLsizei width) { m_width = width; }
-        void set_height(GLsizei height) { m_height = height; }
-        GLsizei width() const { return m_width; }
-        GLsizei height() const { return m_height; }
-
-        Vector<u32>& pixel_data() { return m_pixel_data; }
-        const Vector<u32>& pixel_data() const { return m_pixel_data; }
-
-    private:
-        GLsizei m_width;
-        GLsizei m_height;
-        Vector<u32> m_pixel_data;
-    };
-
-    // To quote the Khronos documentation:
-    // "You could say that a texture object contains a sampler object, which you access through the texture interface."
-    // FIXME: Better name?
-    struct TextureSamplerParamaters {
-        GLint m_min_filter { GL_NEAREST_MIPMAP_LINEAR };
-        GLint m_mag_filter { GL_LINEAR };
-        GLint m_wrap_s_mode { GL_REPEAT };
-        GLint m_wrap_t_mode { GL_REPEAT };
-    };
-
 public:
-    Texture2D() = default;
+    Texture2D()
+        : m_sampler(*this)
+    {
+    }
     ~Texture2D() { }
 
     virtual bool is_texture_2d() const override { return true; }
 
     void upload_texture_data(GLenum target, GLint lod, GLint internal_format, GLsizei width, GLsizei height, GLint border, GLenum format, GLenum type, const GLvoid* pixels);
     void replace_sub_texture_data(GLint lod, GLint xoffset, GLint yoffset, GLsizei width, GLsizei height, GLenum format, GLenum type, const GLvoid* data);
-    FloatVector4 sample_texel(const FloatVector2& uv) const;
+
+    MipMap const& mipmap(unsigned lod) const;
 
     GLenum internal_format() const { return m_internal_format; }
+    Sampler2D const& sampler() const { return m_sampler; }
 
 private:
     template<typename TCallback>
@@ -76,7 +55,7 @@ private:
     // FIXME: Mipmaps are currently unused, but we have the plumbing for it at least
     Array<MipMap, LOG2_MAX_TEXTURE_SIZE> m_mipmaps;
     GLenum m_internal_format;
-    TextureSamplerParamaters m_sampler_params;
+    Sampler2D m_sampler;
 };
 
 }