LibGL: Implement `GL_(UN)PACK_ALIGNMENT`

These enums are used to indicate byte-alignment when reading from and
to textures. The `GL_UNPACK_ROW_LENGTH` value was reimplemented to
support overriding the source data row width.

7 files changed, 81 insertions, 54 deletions

diff --git a/Userland/Libraries/LibGL/GL/gl.h b/Userland/Libraries/LibGL/GL/gl.h
index bf94263349..61aed59565 100644
--- a/Userland/Libraries/LibGL/GL/gl.h
+++ b/Userland/Libraries/LibGL/GL/gl.h
@@ -129,8 +129,10 @@ extern "C" {
 #define GL_GENERATE_MIPMAP_HINT 0x8192
 #define GL_TEXTURE_COMPRESSION_HINT 0x84EF
 
-// Read pixels
+// Reading pixels & unpacking texture patterns
 #define GL_UNPACK_ROW_LENGTH 0x0CF2
+#define GL_UNPACK_ALIGNMENT 0x0CF5
+#define GL_PACK_ALIGNMENT 0x0D05
 
 // Listing enums
 #define GL_COMPILE 0x1300
diff --git a/Userland/Libraries/LibGL/GLContext.h b/Userland/Libraries/LibGL/GLContext.h
index b33c77cdbb..d085c737ed 100644
--- a/Userland/Libraries/LibGL/GLContext.h
+++ b/Userland/Libraries/LibGL/GLContext.h
@@ -85,7 +85,7 @@ public:
     virtual void gl_fogfv(GLenum pname, GLfloat* params) = 0;
     virtual void gl_fogf(GLenum pname, GLfloat params) = 0;
     virtual void gl_fogi(GLenum pname, GLint param) = 0;
-    virtual void gl_pixel_store(GLenum pname, GLfloat param) = 0;
+    virtual void gl_pixel_storei(GLenum pname, GLint param) = 0;
     virtual void gl_scissor(GLint x, GLint y, GLsizei width, GLsizei height) = 0;
 
     virtual void present() = 0;
diff --git a/Userland/Libraries/LibGL/GLUtils.cpp b/Userland/Libraries/LibGL/GLUtils.cpp
index 19556c9b5c..5afd172f5b 100644
--- a/Userland/Libraries/LibGL/GLUtils.cpp
+++ b/Userland/Libraries/LibGL/GLUtils.cpp
@@ -152,7 +152,7 @@ void glPolygonOffset(GLfloat factor, GLfloat units)
 
 void glPixelStorei(GLenum pname, GLint param)
 {
-    g_gl_context->gl_pixel_store(pname, param);
+    g_gl_context->gl_pixel_storei(pname, param);
 }
 
 void glScissor(GLint x, GLint y, GLsizei width, GLsizei height)
diff --git a/Userland/Libraries/LibGL/SoftwareGLContext.cpp b/Userland/Libraries/LibGL/SoftwareGLContext.cpp
index d042e20058..db303f8457 100644
--- a/Userland/Libraries/LibGL/SoftwareGLContext.cpp
+++ b/Userland/Libraries/LibGL/SoftwareGLContext.cpp
@@ -722,7 +722,7 @@ void SoftwareGLContext::gl_tex_image_2d(GLenum target, GLint level, GLint intern
     RETURN_WITH_ERROR_IF((height & (height - 1)) != 0, GL_INVALID_VALUE);
     RETURN_WITH_ERROR_IF(border < 0 || border > 1, GL_INVALID_VALUE);
 
-    m_active_texture_unit->bound_texture_2d()->upload_texture_data(level, internal_format, width, height, border, format, type, data, m_unpack_row_length);
+    m_active_texture_unit->bound_texture_2d()->upload_texture_data(level, internal_format, width, height, border, format, type, data, m_unpack_row_length, m_unpack_alignment);
 }
 
 void SoftwareGLContext::gl_tex_sub_image_2d(GLenum target, GLint level, GLint xoffset, GLint yoffset, GLsizei width, GLsizei height, GLenum format, GLenum type, const GLvoid* data)
@@ -744,7 +744,7 @@ void SoftwareGLContext::gl_tex_sub_image_2d(GLenum target, GLint level, GLint xo
 
     RETURN_WITH_ERROR_IF(xoffset < 0 || yoffset < 0 || xoffset + width > texture->width_at_lod(level) || yoffset + height > texture->height_at_lod(level), GL_INVALID_VALUE);
 
-    texture->replace_sub_texture_data(level, xoffset, yoffset, width, height, format, type, data, m_unpack_row_length);
+    texture->replace_sub_texture_data(level, xoffset, yoffset, width, height, format, type, data, m_unpack_row_length, m_unpack_alignment);
 }
 
 void SoftwareGLContext::gl_tex_parameter(GLenum target, GLenum pname, GLfloat param)
@@ -1167,33 +1167,53 @@ void SoftwareGLContext::gl_read_pixels(GLint x, GLint y, GLsizei width, GLsizei
         return static_cast<GLuint>(0xffffffff * min(max(f, 0.0f), 1.0f));
     };
 
+    u8 component_size = 0;
+    switch (type) {
+    case GL_BYTE:
+    case GL_UNSIGNED_BYTE:
+        component_size = 1;
+        break;
+    case GL_SHORT:
+    case GL_UNSIGNED_SHORT:
+        component_size = 2;
+        break;
+    case GL_INT:
+    case GL_UNSIGNED_INT:
+    case GL_FLOAT:
+        component_size = 4;
+        break;
+    }
+
     if (format == GL_DEPTH_COMPONENT) {
+        auto const row_stride = (width * component_size + m_pack_alignment - 1) / m_pack_alignment * m_pack_alignment;
+
         // Read from depth buffer
         for (GLsizei i = 0; i < height; ++i) {
             for (GLsizei j = 0; j < width; ++j) {
                 float depth = m_rasterizer.get_depthbuffer_value(x + j, y + i);
+                auto char_ptr = reinterpret_cast<char*>(pixels) + i * row_stride + j * component_size;
 
                 switch (type) {
                 case GL_BYTE:
-                    reinterpret_cast<GLchar*>(pixels)[i * width + j] = float_to_i8(depth);
+                    *reinterpret_cast<GLchar*>(char_ptr) = float_to_i8(depth);
                     break;
                 case GL_SHORT:
-                    reinterpret_cast<GLshort*>(pixels)[i * width + j] = float_to_i16(depth);
+                    *reinterpret_cast<GLshort*>(char_ptr) = float_to_i16(depth);
                     break;
                 case GL_INT:
-                    reinterpret_cast<GLint*>(pixels)[i * width + j] = float_to_i32(depth);
+                    *reinterpret_cast<GLint*>(char_ptr) = float_to_i32(depth);
                     break;
                 case GL_UNSIGNED_BYTE:
-                    reinterpret_cast<GLubyte*>(pixels)[i * width + j] = float_to_u8(depth);
+                    *reinterpret_cast<GLubyte*>(char_ptr) = float_to_u8(depth);
                     break;
                 case GL_UNSIGNED_SHORT:
-                    reinterpret_cast<GLushort*>(pixels)[i * width + j] = float_to_u16(depth);
+                    *reinterpret_cast<GLushort*>(char_ptr) = float_to_u16(depth);
                     break;
                 case GL_UNSIGNED_INT:
-                    reinterpret_cast<GLuint*>(pixels)[i * width + j] = float_to_u32(depth);
+                    *reinterpret_cast<GLuint*>(char_ptr) = float_to_u32(depth);
                     break;
                 case GL_FLOAT:
-                    reinterpret_cast<GLfloat*>(pixels)[i * width + j] = min(max(depth, 0.0f), 1.0f);
+                    *reinterpret_cast<GLfloat*>(char_ptr) = min(max(depth, 0.0f), 1.0f);
                     break;
                 }
             }
@@ -1206,7 +1226,6 @@ void SoftwareGLContext::gl_read_pixels(GLint x, GLint y, GLsizei width, GLsizei
     bool write_blue = false;
     bool write_alpha = false;
     size_t component_count = 0;
-    size_t component_size = 0;
     size_t red_offset = 0;
     size_t green_offset = 0;
     size_t blue_offset = 0;
@@ -1259,21 +1278,8 @@ void SoftwareGLContext::gl_read_pixels(GLint x, GLint y, GLsizei width, GLsizei
         break;
     }
 
-    switch (type) {
-    case GL_BYTE:
-    case GL_UNSIGNED_BYTE:
-        component_size = 1;
-        break;
-    case GL_SHORT:
-    case GL_UNSIGNED_SHORT:
-        component_size = 2;
-        break;
-    case GL_INT:
-    case GL_UNSIGNED_INT:
-    case GL_FLOAT:
-        component_size = 4;
-        break;
-    }
+    auto const pixel_bytes = component_size * component_count;
+    auto const row_alignment_bytes = (m_pack_alignment - ((width * pixel_bytes) % m_pack_alignment)) % m_pack_alignment;
 
     char* out_ptr = reinterpret_cast<char*>(pixels);
     for (int i = 0; i < (int)height; ++i) {
@@ -1372,8 +1378,10 @@ void SoftwareGLContext::gl_read_pixels(GLint x, GLint y, GLsizei width, GLsizei
                 break;
             }
 
-            out_ptr += component_size * component_count;
+            out_ptr += pixel_bytes;
         }
+
+        out_ptr += row_alignment_bytes;
     }
 }
 
@@ -1518,6 +1526,9 @@ void SoftwareGLContext::gl_get_integerv(GLenum pname, GLint* data)
     case GL_MAX_TEXTURE_SIZE:
         *data = 4096;
         break;
+    case GL_PACK_ALIGNMENT:
+        *data = m_pack_alignment;
+        break;
     case GL_SCISSOR_BOX: {
         auto scissor_box = m_rasterizer.options().scissor_box;
         *(data + 0) = scissor_box.x();
@@ -1526,6 +1537,12 @@ void SoftwareGLContext::gl_get_integerv(GLenum pname, GLint* data)
         *(data + 3) = scissor_box.height();
         break;
     }
+    case GL_UNPACK_ALIGNMENT:
+        *data = m_unpack_alignment;
+        break;
+    case GL_UNPACK_ROW_LENGTH:
+        *data = m_unpack_row_length;
+        break;
     default:
         // According to the Khronos docs, we always return GL_INVALID_ENUM if we encounter a non-accepted value
         // for `pname`
@@ -2006,14 +2023,22 @@ void SoftwareGLContext::gl_fogi(GLenum pname, GLint param)
     m_rasterizer.set_options(options);
 }
 
-void SoftwareGLContext::gl_pixel_store(GLenum pname, GLfloat param)
+void SoftwareGLContext::gl_pixel_storei(GLenum pname, GLint param)
 {
     // FIXME: Implement missing parameters
     switch (pname) {
+    case GL_PACK_ALIGNMENT:
+        RETURN_WITH_ERROR_IF(param != 1 && param != 2 && param != 4 && param != 8, GL_INVALID_VALUE);
+        m_pack_alignment = param;
+        break;
     case GL_UNPACK_ROW_LENGTH:
         RETURN_WITH_ERROR_IF(param < 0, GL_INVALID_VALUE);
         m_unpack_row_length = static_cast<size_t>(param);
         break;
+    case GL_UNPACK_ALIGNMENT:
+        RETURN_WITH_ERROR_IF(param != 1 && param != 2 && param != 4 && param != 8, GL_INVALID_VALUE);
+        m_unpack_alignment = param;
+        break;
     default:
         RETURN_WITH_ERROR_IF(true, GL_INVALID_ENUM);
         break;
diff --git a/Userland/Libraries/LibGL/SoftwareGLContext.h b/Userland/Libraries/LibGL/SoftwareGLContext.h
index 18f1243538..2faf5bd7b0 100644
--- a/Userland/Libraries/LibGL/SoftwareGLContext.h
+++ b/Userland/Libraries/LibGL/SoftwareGLContext.h
@@ -96,7 +96,7 @@ public:
     virtual void gl_fogfv(GLenum pname, GLfloat* params) override;
     virtual void gl_fogf(GLenum pname, GLfloat param) override;
     virtual void gl_fogi(GLenum pname, GLint param) override;
-    virtual void gl_pixel_store(GLenum pname, GLfloat param) override;
+    virtual void gl_pixel_storei(GLenum pname, GLint param) override;
     virtual void gl_scissor(GLint x, GLint y, GLsizei width, GLsizei height) override;
     virtual void present() override;
 
@@ -265,7 +265,9 @@ private:
     VertexAttribPointer m_client_color_pointer;
     VertexAttribPointer m_client_tex_coord_pointer;
 
-    size_t m_unpack_row_length { 0 };
+    u8 m_pack_alignment { 4 };
+    GLsizei m_unpack_row_length { 0 };
+    u8 m_unpack_alignment { 4 };
 };
 
 }
diff --git a/Userland/Libraries/LibGL/Tex/Texture2D.cpp b/Userland/Libraries/LibGL/Tex/Texture2D.cpp
index 86e58e2784..9300b7a98e 100644
--- a/Userland/Libraries/LibGL/Tex/Texture2D.cpp
+++ b/Userland/Libraries/LibGL/Tex/Texture2D.cpp
@@ -5,14 +5,12 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/Format.h>
 #include <LibGL/GL/gl.h>
 #include <LibGL/Tex/Texture2D.h>
-#include <string.h>
 
 namespace GL {
 
-void Texture2D::upload_texture_data(GLuint lod, GLint internal_format, GLsizei width, GLsizei height, GLint, GLenum format, GLenum type, const GLvoid* pixels, size_t pixels_per_row)
+void Texture2D::upload_texture_data(GLuint lod, GLint internal_format, GLsizei width, GLsizei height, GLint, GLenum format, GLenum type, const GLvoid* pixels, GLsizei pixels_per_row, u8 byte_alignment)
 {
     // NOTE: Some target, format, and internal formats are currently unsupported.
     // Considering we control this library, and `gl.h` itself, we don't need to add any
@@ -24,16 +22,15 @@ void Texture2D::upload_texture_data(GLuint lod, GLint internal_format, GLsizei w
     mip.pixel_data().resize(width * height);
 
     // No pixel data was supplied leave the texture memory uninitialized.
-    if (pixels == nullptr) {
+    if (pixels == nullptr)
         return;
-    }
 
     m_internal_format = internal_format;
 
-    replace_sub_texture_data(lod, 0, 0, width, height, format, type, pixels, pixels_per_row);
+    replace_sub_texture_data(lod, 0, 0, width, height, format, type, pixels, pixels_per_row, byte_alignment);
 }
 
-void Texture2D::replace_sub_texture_data(GLuint lod, GLint xoffset, GLint yoffset, GLsizei width, GLsizei height, GLenum format, GLenum type, const GLvoid* pixels, size_t pixels_per_row)
+void Texture2D::replace_sub_texture_data(GLuint lod, GLint xoffset, GLint yoffset, GLsizei width, GLsizei height, GLenum format, GLenum type, const GLvoid* pixels, GLsizei pixels_per_row, u8 byte_alignment)
 {
     auto& mip = m_mipmaps[lod];
 
@@ -41,8 +38,17 @@ void Texture2D::replace_sub_texture_data(GLuint lod, GLint xoffset, GLint yoffse
     VERIFY(type == GL_UNSIGNED_BYTE);
     VERIFY(lod < m_mipmaps.size());
     VERIFY(xoffset >= 0 && yoffset >= 0 && xoffset + width <= mip.width() && yoffset + height <= mip.height());
+    VERIFY(pixels_per_row == 0 || pixels_per_row >= xoffset + width);
+
+    // Calculate row offset at end to fit alignment
+    int const physical_width = pixels_per_row > 0 ? pixels_per_row : width;
+    u8 const component_size_bytes = sizeof(u8);
+    u8 const component_count = (format == GL_RGBA || format == GL_BGRA) ? 4 : 3;
+    size_t const physical_width_bytes = physical_width * component_count * component_size_bytes;
+    size_t const row_remainder_bytes = (physical_width - width) * component_count * component_size_bytes
+        + (byte_alignment - physical_width_bytes % byte_alignment) % byte_alignment;
 
-    const u8* pixel_byte_array = reinterpret_cast<const u8*>(pixels);
+    u8 const* pixel_byte_array = reinterpret_cast<u8 const*>(pixels);
 
     if (format == GL_RGBA) {
         for (auto y = yoffset; y < yoffset + height; y++) {
@@ -56,9 +62,7 @@ void Texture2D::replace_sub_texture_data(GLuint lod, GLint xoffset, GLint yoffse
                 mip.pixel_data()[y * mip.width() + x] = pixel;
             }
 
-            if (pixels_per_row > 0) {
-                pixel_byte_array += (pixels_per_row - width) * 4;
-            }
+            pixel_byte_array += row_remainder_bytes;
         }
     } else if (format == GL_BGRA) {
         for (auto y = yoffset; y < yoffset + height; y++) {
@@ -72,9 +76,7 @@ void Texture2D::replace_sub_texture_data(GLuint lod, GLint xoffset, GLint yoffse
                 mip.pixel_data()[y * mip.width() + x] = pixel;
             }
 
-            if (pixels_per_row > 0) {
-                pixel_byte_array += (pixels_per_row - width) * 4;
-            }
+            pixel_byte_array += row_remainder_bytes;
         }
     } else if (format == GL_BGR) {
         for (auto y = yoffset; y < yoffset + height; y++) {
@@ -88,9 +90,7 @@ void Texture2D::replace_sub_texture_data(GLuint lod, GLint xoffset, GLint yoffse
                 mip.pixel_data()[y * mip.width() + x] = pixel;
             }
 
-            if (pixels_per_row > 0) {
-                pixel_byte_array += (pixels_per_row - width) * 3;
-            }
+            pixel_byte_array += row_remainder_bytes;
         }
     } else if (format == GL_RGB) {
         for (auto y = yoffset; y < yoffset + height; y++) {
@@ -104,9 +104,7 @@ void Texture2D::replace_sub_texture_data(GLuint lod, GLint xoffset, GLint yoffse
                 mip.pixel_data()[y * mip.width() + x] = pixel;
             }
 
-            if (pixels_per_row > 0) {
-                pixel_byte_array += (pixels_per_row - width) * 3;
-            }
+            pixel_byte_array += row_remainder_bytes;
         }
     } else {
         VERIFY_NOT_REACHED();
diff --git a/Userland/Libraries/LibGL/Tex/Texture2D.h b/Userland/Libraries/LibGL/Tex/Texture2D.h
index 2c79fb6e3b..618c8c7086 100644
--- a/Userland/Libraries/LibGL/Tex/Texture2D.h
+++ b/Userland/Libraries/LibGL/Tex/Texture2D.h
@@ -35,8 +35,8 @@ public:
 
     virtual bool is_texture_2d() const override { return true; }
 
-    void upload_texture_data(GLuint lod, GLint internal_format, GLsizei width, GLsizei height, GLint border, GLenum format, GLenum type, const GLvoid* pixels, size_t pixels_per_row);
-    void replace_sub_texture_data(GLuint lod, GLint xoffset, GLint yoffset, GLsizei width, GLsizei height, GLenum format, GLenum type, const GLvoid* pixels, size_t pixels_per_row);
+    void upload_texture_data(GLuint lod, GLint internal_format, GLsizei width, GLsizei height, GLint border, GLenum format, GLenum type, const GLvoid* pixels, GLsizei pixels_per_row, u8 byte_alignment);
+    void replace_sub_texture_data(GLuint lod, GLint xoffset, GLint yoffset, GLsizei width, GLsizei height, GLenum format, GLenum type, const GLvoid* pixels, GLsizei pixels_per_row, u8 byte_alignment);
 
     MipMap const& mipmap(unsigned lod) const;