Set up transformations in vertex shader

BUILD.md

@@ -125,11 +125,11 @@ Once CMake finishes, the built files will be put in `builds/mac/Descent3/Debug`
     * If you would like to manage the code dependencies yourself:
         * APT users
             ```sh
-            sudo apt install -y --no-install-recommends libsdl2-dev zlib1g-dev libgtest-dev
+            sudo apt install -y --no-install-recommends libsdl2-dev zlib1g-dev libgtest-dev libglm-dev
             ```
         * DNF users
             ```sh
-            sudo dnf install -y SDL2-devel zlib-devel gtest
+            sudo dnf install -y SDL2-devel zlib-devel gtest glm-devel
             ```
 
 3. **Clone the Descent3 source code.**

CMakeLists.txt

@@ -131,6 +131,7 @@ if(CMAKE_CXX_COMPILER_ID MATCHES "Clang" OR CMAKE_CXX_COMPILER_ID STREQUAL "GNU"
   add_compile_options("-Wno-multichar;-Wall")
 endif()
 
+find_package(glm REQUIRED)
 find_package(SDL2 REQUIRED)
 # Some versions of the SDL2 find_package set SDL2_INCLUDE_DIR and some set a plural SDL2_INCLUDE_DIRS. Check both.
 message("SDL2 Include Dir is ${SDL2_INCLUDE_DIR} ${SDL2_INCLUDE_DIRS}")

renderer/CMakeLists.txt

@@ -33,6 +33,7 @@ set(CPPS
 add_library(renderer STATIC ${HEADERS} ${CPPS})
 target_include_directories(renderer PRIVATE ${GENERATED_HEADERS})
 target_link_libraries(renderer PRIVATE
+  glm::glm
   SDL2::SDL2
   bitmap
   ddio

renderer/HardwareOpenGL.cpp

@@ -77,7 +77,29 @@ struct Renderer {
     shader_.Use();
   }
 
+  /**
+   * Sets the vertex transformation matrices. Takes all three of the MVP matrices at once, in order to avoid
+   * multiple SetUniform operations. Pass std::nullopt for any matrices that should not be altered.
+   */
+  void setTransform(std::optional<glm::mat4x4> const &model, std::optional<glm::mat4x4> const &view,
+                    std::optional<glm::mat4x4> const &projection) {
+    if (model) {
+      model_ = *model;
+    }
+    if (view) {
+      view_ = *view;
+    }
+    if (projection) {
+      projection_ = *projection;
+    }
+
+    shader_.setUniformMat4f("u_transform", projection_ * view_ * model_);
+  }
+
 private:
+  glm::mat4x4 model_;
+  glm::mat4x4 view_;
+  glm::mat4x4 projection_;
   ShaderProgram<PosColorUV2Vertex> shader_;
 };
 std::optional<Renderer> gRenderer;
@@ -1933,18 +1955,11 @@ void rend_TransformSetToPassthru(void) {
   int height = gpu_state.screen_height;
 
   // TODO: Generalize
-  // Projection
-  dglMatrixMode(GL_PROJECTION);
-  dglLoadIdentity();
-  dglOrtho((GLfloat)0.0f, (GLfloat)(width), (GLfloat)(height), (GLfloat)0.0f, 0.0f, 1.0f);
+  gRenderer->setTransform(glm::mat4x4{1}, glm::mat4x4{1}, glm::ortho<float>(0, width, height, 0, 0, 1));
 
   // Viewport
   dglViewport(0, 0, width, height);
   dglScissor(0, 0, width, height);
-
-  // ModelView
-  dglMatrixMode(GL_MODELVIEW);
-  dglLoadIdentity();
 }
 
 void rend_TransformSetViewport(int lx, int ty, int width, int height) {
@@ -1952,11 +1967,9 @@ void rend_TransformSetViewport(int lx, int ty, int width, int height) {
 }
 
 void rend_TransformSetProjection(float trans[4][4]) {
-  dglMatrixMode(GL_PROJECTION);
-  dglLoadMatrixf(&trans[0][0]);
+  gRenderer->setTransform(std::nullopt, std::nullopt, glm::make_mat4x4(&trans[0][0]));
 }
 
 void rend_TransformSetModelView(float trans[4][4]) {
-  dglMatrixMode(GL_MODELVIEW);
-  dglLoadMatrixf(&trans[0][0]);
+  gRenderer->setTransform(glm::make_mat4x4(&trans[0][0]), glm::mat4x4{1}, std::nullopt);
 }

renderer/ShaderProgram.h

@@ -22,6 +22,9 @@
 #include <functional>
 #include <stdexcept>
 #include <string>
+#include <unordered_map>
+#include <glm/mat4x4.hpp>
+#include <glm/gtc/type_ptr.hpp>
 #include "dyna_gl.h"
 #include "holder.h"
 
@@ -167,7 +170,25 @@ struct ShaderProgram {
     dglUseProgram(0);
   }
 
+  void setUniformMat4f(std::string const& name, glm::mat4x4 const& matrix) {
+    dglUniformMatrix4fv(getUniformId(name), 1, GL_FALSE, glm::value_ptr(matrix));
+  }
+
 private:
+  GLint getUniformId(std::string const& name) {
+    auto it = uniform_cache_.find(name);
+    if (it != uniform_cache_.end()) {
+      return it->second;
+    }
+
+    it = uniform_cache_.emplace(name, dglGetUniformLocation(id_, name.c_str())).first;
+    if (it->second != -1) {
+      return it->second;
+    }
+
+    throw std::runtime_error("uniform " + name + " nonexistent or inactive");
+  }
+
   static void DeleteProgram(GLuint id) {
     dglDeleteProgram(id);
   }
@@ -176,4 +197,5 @@ private:
   Shader<GL_VERTEX_SHADER> vertex_;
   Shader<GL_FRAGMENT_SHADER> fragment_;
   VertexBuffer<V> vbo_;
+  std::unordered_map<std::string, GLint> uniform_cache_;
 };

renderer/dyna_gl.h

@@ -191,12 +191,9 @@ DYNAEXTERN(glGetShaderInfoLog);
 DYNAEXTERN(glGetShaderiv);
 DYNAEXTERN(glGetString);
 DYNAEXTERN(glGetStringi);
+DYNAEXTERN(glGetUniformLocation);
 DYNAEXTERN(glHint);
 DYNAEXTERN(glLinkProgram);
-DYNAEXTERN(glLoadIdentity);
-DYNAEXTERN(glLoadMatrixf);
-DYNAEXTERN(glMatrixMode);
-DYNAEXTERN(glOrtho);
 DYNAEXTERN(glPixelStorei);
 DYNAEXTERN(glPolygonOffset);
 DYNAEXTERN(glReadPixels);
@@ -209,6 +206,7 @@ DYNAEXTERN(glTexEnvf);
 DYNAEXTERN(glTexImage2D);
 DYNAEXTERN(glTexParameteri);
 DYNAEXTERN(glTexSubImage2D);
+DYNAEXTERN(glUniformMatrix4fv);
 DYNAEXTERN(glUseProgram);
 DYNAEXTERN(glVertexAttribPointer);
 DYNAEXTERN(glVertexPointer);

renderer/shaders/vertex.glsl

@@ -23,7 +23,9 @@ in vec4 in_color;
 in vec2 in_uv0;
 in vec2 in_uv1;
 
+uniform mat4 u_transform;
+
 void main()
 {
-    gl_Position = vec4(0);
+    gl_Position = u_transform * vec4(in_pos, 1);
 }

vcpkg.json

@@ -1,6 +1,7 @@
 {
   "builtin-baseline": "198d68dbcc6c907cb3d0b9b1d93c3df6ecf93c62",
   "dependencies": [
+    "glm",
     "gtest",
     "zlib",
     {