opengl: support for webgl 2

updateVramTexture LUT conversion for slower path (Android and Web)
fix shader version header

externals/glad/include/opengl.h

@@ -0,0 +1,6 @@
+#pragma once
+#ifdef __EMSCRIPTEN__
+#include <GLES3/gl3.h>
+#else 
+#include <glad/glad.h>
+#endif

src/imgui/imgui_impl_sdl_gl3.cpp

@@ -49,7 +49,7 @@
 // SDL,GL3W
 #include <SDL.h>
 #include <SDL_syswm.h>
-#include <glad/glad.h>
+#include <opengl.h>
 
 // SDL data
 static Uint64       g_Time = 0;
@@ -439,9 +439,12 @@ void ImGui_ImplSdlGL3_NewFrame(SDL_Window* window)
     int w, h;
     static int display_w = 0, display_h = 0;
     SDL_GetWindowSize(window, &w, &h);
-    // if (display_w == 0 || display_h == 0) { // web optimization
+#ifdef __EMSCRIPTEN
+    if (display_w == 0 || display_h == 0) // web optimization
+#endif
+    {
         SDL_GL_GetDrawableSize(window, &display_w, &display_h);
-    // }
+    }
     io.DisplaySize = ImVec2((float)w, (float)h);
     io.DisplayFramebufferScale = ImVec2(w > 0 ? ((float)display_w / w) : 0, h > 0 ? ((float)display_h / h) : 0);
 

src/platform/windows/gui/images.h

@@ -1,6 +1,6 @@
 #pragma once
+#include <opengl.h>
 #include <string>
-#include <glad/glad.h>
 
 #ifdef __APPLE__
 #include <experimental/optional>

src/renderer/opengl/opengl.cpp

@@ -26,7 +26,13 @@ bool OpenGL::init() {
 
 void OpenGL::deinit() { bus.unlistenAll(busToken); }
 
-bool OpenGL::loadExtensions() { return gladLoadGLLoader(SDL_GL_GetProcAddress) != 0; }
+bool OpenGL::loadExtensions() {
+#ifdef __glad_h_
+    return gladLoadGLLoader(SDL_GL_GetProcAddress) != 0;
+#else
+    return true;
+#endif
+}
 
 bool OpenGL::loadShaders() {
     // PS1 GPU in Shader simulation
@@ -58,12 +64,14 @@ bool OpenGL::setup() {
         return false;
     }
 
+#ifdef __glad_h_
     // Check actual version of OpenGL context
     if (GLVersion.major * 10 + GLVersion.minor < VERSION_MAJOR * 10 + VERSION_MINOR) {
         printf("Unable to initialize OpenGL context for version %d.%d (got %d.%d)\n", VERSION_MAJOR, VERSION_MINOR, GLVersion.major,
                GLVersion.minor);
         return false;
     }
+#endif
 
     if (!loadShaders()) return false;
 
@@ -98,9 +106,11 @@ bool OpenGL::setup() {
     blitBuffer = std::make_unique<Buffer>(makeBlitBuf().size() * sizeof(BlitStruct));
 
     // Try native texture
+#ifdef GL_UNSIGNED_SHORT_1_5_5_5_REV
     vramTex = std::make_unique<Texture>(1024, 512, GL_RGBA, GL_RGBA, GL_UNSIGNED_SHORT_1_5_5_5_REV, false);
+#endif
 
-    if (vramTex->isCreated()) {
+    if (vramTex && vramTex->isCreated()) {
         supportNativeTexture = true;
     } else {
         // Use compability mode
@@ -240,6 +250,16 @@ void OpenGL::update24bitTexture(gpu::GPU* gpu) {
     vramTex->update(vramUnpacked.data());
 }
 
+constexpr std::array<float, 32> generateFloatLUT() {
+    std::array<float, 32> lut = {{0}};
+    for (int i = 0; i < 32; i++) {
+        lut[i] = i / 31.f;
+    }
+    return lut;
+}
+
+const std::array<float, 32> floatLUT = generateFloatLUT();
+
 void OpenGL::updateVramTexture(gpu::GPU* gpu) {
     if (supportNativeTexture) {
         vramTex->update(gpu->vram.data());
@@ -257,10 +277,10 @@ void OpenGL::updateVramTexture(gpu::GPU* gpu) {
         for (int x = 0; x < gpu::VRAM_WIDTH; x++) {
             PSXColor c = gpu->vram[y * gpu::VRAM_WIDTH + x];
 
-            vramUnpacked[(y * gpu::VRAM_WIDTH + x) * 4 + 0] = c.r / 31.f;
-            vramUnpacked[(y * gpu::VRAM_WIDTH + x) * 4 + 1] = c.g / 31.f;
-            vramUnpacked[(y * gpu::VRAM_WIDTH + x) * 4 + 2] = c.b / 31.f;
-            vramUnpacked[(y * gpu::VRAM_WIDTH + x) * 4 + 3] = (float)c.k;
+            vramUnpacked[(y * gpu::VRAM_WIDTH + x) * 4 + 0] = floatLUT[c.r];
+            vramUnpacked[(y * gpu::VRAM_WIDTH + x) * 4 + 1] = floatLUT[c.g];
+            vramUnpacked[(y * gpu::VRAM_WIDTH + x) * 4 + 2] = floatLUT[c.b];
+            vramUnpacked[(y * gpu::VRAM_WIDTH + x) * 4 + 3] = floatLUT[c.k * 31];
         }
     }
     vramTex->update(vramUnpacked.data());

src/renderer/opengl/opengl.h

@@ -1,5 +1,5 @@
 #pragma once
-#include <glad/glad.h>
+#include <opengl.h>
 #include <memory>
 #include "device/gpu/gpu.h"
 #include "shader/buffer.h"

src/renderer/opengl/shader/attribute.h

@@ -1,5 +1,5 @@
 #pragma once
-#include "glad/glad.h"
+#include <opengl.h>
 
 class Attribute {
     GLuint id;

src/renderer/opengl/shader/buffer.h

@@ -1,5 +1,5 @@
 #pragma once
-#include <glad/glad.h>
+#include <opengl.h>
 
 class Buffer {
     GLuint id;

src/renderer/opengl/shader/framebuffer.h

@@ -1,5 +1,5 @@
 #pragma once
-#include <glad/glad.h>
+#include <opengl.h>
 
 class Framebuffer {
     GLuint id;

src/renderer/opengl/shader/program.h

@@ -1,5 +1,5 @@
 #pragma once
-#include <glad/glad.h>
+#include <opengl.h>
 #include <unordered_map>
 #include <vector>
 #include "attribute.h"

src/renderer/opengl/shader/shader.cpp

@@ -4,16 +4,14 @@
 #include "utils/file.h"
 
 #ifdef USE_OPENGLES
-const char* Shader::header = R"EOF(
-#version 300 es
+const char* Shader::header = R"EOF(#version 300 es
 #ifdef GL_ES
 precision mediump float;
 #endif
 
 )EOF";
 #else
-const char* Shader::header = R"EOF(
-#version 150
+const char* Shader::header = R"EOF(#version 150
 
 )EOF";
 #endif

src/renderer/opengl/shader/shader.h

@@ -1,5 +1,5 @@
 #pragma once
-#include <glad/glad.h>
+#include <opengl.h>
 #include <string>
 
 enum class ShaderType { Vertex, Fragment };

src/renderer/opengl/shader/texture.h

@@ -1,5 +1,5 @@
 #pragma once
-#include <glad/glad.h>
+#include <opengl.h>
 
 class Texture {
     GLuint id;

src/renderer/opengl/shader/uniform.h

@@ -1,6 +1,6 @@
 #pragma once
+#include <opengl.h>
 #include <tuple>
-#include "glad/glad.h"
 
 class Uniform {
     GLuint id;