From 5e27da20f43643d4e2ec01af5c1de423cef06cd3 Mon Sep 17 00:00:00 2001
From: Stephan Unverwerth <s.unverwerth@serenityos.org>
Date: Mon, 16 Aug 2021 15:13:19 +0200
Subject: [PATCH] LibGL: Fix glTexCoord behaviour

glTexCoord should behave like glColor. It only updates a gl context
variable that contains the current texture coordinates. The vertex is
only actually created once glVertex is called.
---
 Userland/Applications/3DFileViewer/Mesh.cpp    | 10 +++++-----
 Userland/Libraries/LibGL/SoftwareGLContext.cpp | 11 +++++------
 Userland/Libraries/LibGL/SoftwareGLContext.h   |  1 +
 3 files changed, 11 insertions(+), 11 deletions(-)

diff --git a/Userland/Applications/3DFileViewer/Mesh.cpp b/Userland/Applications/3DFileViewer/Mesh.cpp
index 20e8cec61a4..0bae181b072 100644
--- a/Userland/Applications/3DFileViewer/Mesh.cpp
+++ b/Userland/Applications/3DFileViewer/Mesh.cpp
@@ -69,6 +69,9 @@ void Mesh::draw(float uv_scale)
         glBegin(GL_TRIANGLES);
         glColor4f(color.x(), color.y(), color.z(), color.w());
 
+        if (is_textured())
+            glTexCoord2f(m_tex_coords.at(m_triangle_list[i].tex_coord_index0).u * uv_scale, (1.0f - m_tex_coords.at(m_triangle_list[i].tex_coord_index0).v) * uv_scale);
+
         // Vertex 1
         glVertex3f(
             m_vertex_list.at(m_triangle_list[i].a).x,
@@ -76,7 +79,7 @@ void Mesh::draw(float uv_scale)
             m_vertex_list.at(m_triangle_list[i].a).z);
 
         if (is_textured())
-            glTexCoord2f(m_tex_coords.at(m_triangle_list[i].tex_coord_index0).u * uv_scale, (1.0f - m_tex_coords.at(m_triangle_list[i].tex_coord_index0).v) * uv_scale);
+            glTexCoord2f(m_tex_coords.at(m_triangle_list[i].tex_coord_index1).u * uv_scale, (1.0f - m_tex_coords.at(m_triangle_list[i].tex_coord_index1).v) * uv_scale);
 
         // Vertex 2
         glVertex3f(
@@ -85,7 +88,7 @@ void Mesh::draw(float uv_scale)
             m_vertex_list.at(m_triangle_list[i].b).z);
 
         if (is_textured())
-            glTexCoord2f(m_tex_coords.at(m_triangle_list[i].tex_coord_index1).u * uv_scale, (1.0f - m_tex_coords.at(m_triangle_list[i].tex_coord_index1).v) * uv_scale);
+            glTexCoord2f(m_tex_coords.at(m_triangle_list[i].tex_coord_index2).u * uv_scale, (1.0f - m_tex_coords.at(m_triangle_list[i].tex_coord_index2).v) * uv_scale);
 
         // Vertex 3
         glVertex3f(
@@ -93,9 +96,6 @@ void Mesh::draw(float uv_scale)
             m_vertex_list.at(m_triangle_list[i].c).y,
             m_vertex_list.at(m_triangle_list[i].c).z);
 
-        if (is_textured())
-            glTexCoord2f(m_tex_coords.at(m_triangle_list[i].tex_coord_index2).u * uv_scale, (1.0f - m_tex_coords.at(m_triangle_list[i].tex_coord_index2).v) * uv_scale);
-
         glEnd();
     }
 }
diff --git a/Userland/Libraries/LibGL/SoftwareGLContext.cpp b/Userland/Libraries/LibGL/SoftwareGLContext.cpp
index 323955520c8..be2e8151fdc 100644
--- a/Userland/Libraries/LibGL/SoftwareGLContext.cpp
+++ b/Userland/Libraries/LibGL/SoftwareGLContext.cpp
@@ -555,19 +555,18 @@ void SoftwareGLContext::gl_vertex(GLdouble x, GLdouble y, GLdouble z, GLdouble w
 
     // FIXME: This is to suppress any -Wunused errors
     vertex.w = 0.0f;
-    vertex.u = 0.0f;
-    vertex.v = 0.0f;
+    vertex.u = m_current_vertex_tex_coord.x();
+    vertex.v = m_current_vertex_tex_coord.y();
 
     vertex_list.append(vertex);
 }
 
 // FIXME: We need to add `r` and `q` to our GLVertex?!
-void SoftwareGLContext::gl_tex_coord(GLfloat s, GLfloat t, GLfloat, GLfloat)
+void SoftwareGLContext::gl_tex_coord(GLfloat s, GLfloat t, GLfloat r, GLfloat q)
 {
-    auto& vertex = vertex_list.last(); // Get the last created vertex
+    APPEND_TO_CALL_LIST_AND_RETURN_IF_NEEDED(gl_tex_coord, s, t, r, q);
 
-    vertex.u = s;
-    vertex.v = t;
+    m_current_vertex_tex_coord = { s, t, r, q };
 }
 
 void SoftwareGLContext::gl_viewport(GLint x, GLint y, GLsizei width, GLsizei height)
diff --git a/Userland/Libraries/LibGL/SoftwareGLContext.h b/Userland/Libraries/LibGL/SoftwareGLContext.h
index abcdf7f19e2..7875ac38443 100644
--- a/Userland/Libraries/LibGL/SoftwareGLContext.h
+++ b/Userland/Libraries/LibGL/SoftwareGLContext.h
@@ -119,6 +119,7 @@ private:
     FloatVector4 m_clear_color = { 0.0f, 0.0f, 0.0f, 0.0f };
     double m_clear_depth = { 1.0 };
     FloatVector4 m_current_vertex_color = { 1.0f, 1.0f, 1.0f, 1.0f };
+    FloatVector4 m_current_vertex_tex_coord = { 0.0f, 0.0f, 0.0f, 0.0f };
 
     Vector<GLVertex, 96> vertex_list;
     Vector<GLTriangle, 32> triangle_list;