get somewhere with this

hahahahahahhhhh

except it's still upside-down

src/GPU_OpenGL.cpp

@@ -26,7 +26,171 @@
 
 namespace GPU
 {
+namespace GLCompositor
+{
 
-// shit goes here
+int Scale;
+int ScreenH, ScreenW;
+
+GLuint CompShader[1][3];
+GLuint CompScaleLoc[1];
+
+GLuint CompVertexBufferID;
+GLuint CompVertexArrayID;
+float CompVertices[2 * 3*2 * 2]; // position
+
+GLuint CompScreenInputTex;
+GLuint CompScreenOutputTex;
+GLuint CompScreenOutputFB;
+
+
+bool Init()
+{
+    if (!OpenGL_BuildShaderProgram(kCompositorVS, kCompositorFS_Nearest, CompShader[0], "CompositorShader"))
+        return false;
+
+    for (int i = 0; i < 1; i++)
+    {
+        glBindAttribLocation(CompShader[i][2], 0, "vPosition");
+        glBindFragDataLocation(CompShader[i][2], 0, "oColor");
+
+        if (!OpenGL_LinkShaderProgram(CompShader[i]))
+            return false;
+
+        CompScaleLoc[i] = glGetUniformLocation(CompShader[i][2], "u3DScale");
+    }
+
+#define SETVERTEX(i, x, y) \
+    CompVertices[2*(i) + 0] = x; \
+    CompVertices[2*(i) + 1] = y;
+
+    // top screen
+    SETVERTEX(0, -1, 1);
+    SETVERTEX(1, 1, 0);
+    SETVERTEX(2, 1, 1);
+    SETVERTEX(3, -1, 1);
+    SETVERTEX(4, -1, 0);
+    SETVERTEX(5, 1, 0);
+
+    // bottom screen
+    SETVERTEX(6, -1, 0);
+    SETVERTEX(7, 1, -1);
+    SETVERTEX(8, 1, 0);
+    SETVERTEX(9, -1, 0);
+    SETVERTEX(10, -1, -1);
+    SETVERTEX(11, 1, -1);
+
+#undef SETVERTEX
+
+    glGenBuffers(1, &CompVertexBufferID);
+    glBindBuffer(GL_ARRAY_BUFFER, CompVertexBufferID);
+    glBufferData(GL_ARRAY_BUFFER, sizeof(CompVertices), CompVertices, GL_STATIC_DRAW);
+
+    glGenVertexArrays(1, &CompVertexArrayID);
+    glBindVertexArray(CompVertexArrayID);
+    glEnableVertexAttribArray(0); // position
+    glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, 2*4, (void*)(0));
+
+    glGenFramebuffers(1, &CompScreenOutputFB);
+
+    glGenTextures(1, &CompScreenInputTex);
+    glActiveTexture(GL_TEXTURE0);
+    glBindTexture(GL_TEXTURE_2D, CompScreenInputTex);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
+    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8UI, 256*3 + 1, 192*2, 0, GL_RGBA_INTEGER, GL_UNSIGNED_BYTE, NULL);
+
+    glGenTextures(1, &CompScreenOutputTex);
+    glBindTexture(GL_TEXTURE_2D, CompScreenOutputTex);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
+
+    return true;
+}
+
+void DeInit()
+{
+    glDeleteFramebuffers(1, &CompScreenOutputFB);
+    glDeleteTextures(1, &CompScreenInputTex);
+    glDeleteTextures(1, &CompScreenOutputTex);
+
+    glDeleteVertexArrays(1, &CompVertexArrayID);
+    glDeleteBuffers(1, &CompVertexBufferID);
+
+    for (int i = 0; i < 1; i++)
+        OpenGL_DeleteShaderProgram(CompShader[i]);
+}
+
+void Reset()
+{
+}
+
+
+void UpdateDisplaySettings()
+{
+    int scale = Config::GL_ScaleFactor;
+
+    Scale = scale;
+    ScreenW = 256 * scale;
+    ScreenH = 384 * scale;
+
+    glBindTexture(GL_TEXTURE_2D, CompScreenOutputTex);
+    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, ScreenW, ScreenH, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL);
+
+    GLenum fbassign[] = {GL_COLOR_ATTACHMENT0};
+    glBindFramebuffer(GL_FRAMEBUFFER, CompScreenOutputFB);
+    glFramebufferTexture(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, CompScreenOutputTex, 0);
+    glDrawBuffers(1, fbassign);
+}
+
+
+void RenderFrame()
+{printf("0: error %04X\n", glGetError());
+    glBindFramebuffer(GL_FRAMEBUFFER, CompScreenOutputFB);
+printf("1: error %04X\n", glGetError());
+    glDisable(GL_DEPTH_TEST);
+    glDisable(GL_STENCIL_TEST);
+    glDisable(GL_BLEND);
+    glColorMaski(0, GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE);
+
+    glViewport(0, 0, ScreenW, ScreenH);
+printf("2: error %04X\n", glGetError());
+    // TODO: select more shaders (filtering, etc)
+    OpenGL_UseShaderProgram(CompShader[0]);
+    glUniform1ui(CompScaleLoc[0], Scale);
+printf("3: error %04X\n", glGetError());
+    //if (RunningSomething)
+    {
+        int frontbuf = GPU::FrontBuffer;
+        glActiveTexture(GL_TEXTURE0);
+        glBindTexture(GL_TEXTURE_2D, CompScreenInputTex);
+printf("4: error %04X\n", glGetError());
+        if (GPU::Framebuffer[frontbuf][0] && GPU::Framebuffer[frontbuf][1])
+        {
+            glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, 256*3 + 1, 192, GL_RGBA_INTEGER,
+                            GL_UNSIGNED_BYTE, GPU::Framebuffer[frontbuf][0]);
+            glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 192, 256*3 + 1, 192, GL_RGBA_INTEGER,
+                            GL_UNSIGNED_BYTE, GPU::Framebuffer[frontbuf][1]);
+        }
+printf("5: error %04X\n", glGetError());
+        glActiveTexture(GL_TEXTURE1);
+        GPU3D::GLRenderer::SetupAccelFrame();
+printf("6: error %04X\n", glGetError());
+        glBindBuffer(GL_ARRAY_BUFFER, CompVertexBufferID);
+        glBindVertexArray(CompVertexArrayID);
+        glDrawArrays(GL_TRIANGLES, 0, 4*3);
+        printf("7: error %04X\n", glGetError());
+    }
+}
+
+void BindOutputTexture()
+{
+    glBindTexture(GL_TEXTURE_2D, CompScreenOutputTex);
+}
 
 }
+}