Fix my blended rendering on Tegra 2 (and arguably globally)

Android/app/build.gradle

@@ -27,8 +27,8 @@ android {
         applicationId "org.deadc0de.apple2ix.basic"
         minSdkVersion 10
         targetSdkVersion 21
-        versionCode 5
-        versionName "1.0.2"
+        versionCode 6
+        versionName "1.0.3"
         ndk {
             moduleName "apple2ix"
         }

src/video/Basic.fsh

@@ -24,18 +24,12 @@ uniform float aValue;
 uniform sampler2D texture;
 
 #if __VERSION__ >= 140
-#define OUTPUT_TEXTURE(TEX) \
-        vec4 tex = texture(TEX, varTexcoord.st, 0.0); \
-        fragColor = vec4(tex.r, tex.g, tex.b, tex.a*aValue)
-#define OUTPUT_RED() \
-        fragColor = vec4(1.0, 0.0, 0.0, 1.0)
+#define OUTPUT_TEXTURE(TEX) vec4 tex = texture(TEX, varTexcoord.st, 0.0); fragColor = vec4(tex.r, tex.g, tex.b, tex.a*aValue)
 #else
 #define OUTPUT_TEXTURE(TEX) vec4 tex = texture2D(TEX, varTexcoord.st, 0.0); gl_FragColor = vec4(tex.r, tex.g, tex.b, tex.a*aValue)
-#define OUTPUT_RED() gl_FragColor = vec4(1.0, 0.0, 0.0, 1.0)
 #endif
 
 void main(void)
 {
     OUTPUT_TEXTURE(texture);
-    //OUTPUT_RED(); -- WTF is this failing?
 }

src/video/glvideo.c

@@ -46,6 +46,9 @@ static GLuint texcoordBufferName = UNINITIALIZED_GL;
 static GLuint elementBufferName = UNINITIALIZED_GL;
 static GLModel *crtModel = NULL;
 
+static GLuint vertexShader = UNINITIALIZED_GL;
+static GLuint fragShader = UNINITIALIZED_GL;
+
 static video_backend_s glvideo_backend = { 0 };
 
 #if USE_GLUT
@@ -323,7 +326,7 @@ static GLuint _build_program(demoSource *vertexSource, demoSource *fragmentSourc
         sprintf(sourceString, "%s", vertexSource->string);
     }
 
-    GLuint vertexShader = glCreateShader(GL_VERTEX_SHADER);
+    vertexShader = glCreateShader(GL_VERTEX_SHADER);
     glShaderSource(vertexShader, 1, (const GLchar **)&(sourceString), NULL);
     glCompileShader(vertexShader);
     glGetShaderiv(vertexShader, GL_INFO_LOG_LENGTH, &logLength);
@@ -362,7 +365,7 @@ static GLuint _build_program(demoSource *vertexSource, demoSource *fragmentSourc
         sprintf(sourceString, "%s", fragmentSource->string);
     }
 
-    GLuint fragShader = glCreateShader(GL_FRAGMENT_SHADER);
+    fragShader = glCreateShader(GL_FRAGMENT_SHADER);
     glShaderSource(fragShader, 1, (const GLchar **)&(sourceString), NULL);
     glCompileShader(fragShader);
     glGetShaderiv(fragShader, GL_INFO_LOG_LENGTH, &logLength);
@@ -398,17 +401,6 @@ static GLuint _build_program(demoSource *vertexSource, demoSource *fragmentSourc
         free(log);
     }
 
-    glDetachShader(prgName, vertexShader);
-    glDetachShader(prgName, fragShader);
-
-    // Delete the vertex shader since it is now attached and linked
-    // to the program, which will retain a reference to it
-    glDeleteShader(vertexShader);
-
-    // Delete the fragment shader since it is now attached and linked
-    // to the program, which will retain a reference to it
-    glDeleteShader(fragShader);
-
     glGetProgramiv(prgName, GL_LINK_STATUS, &status);
     if (status == 0) {
         LOG("Failed to link program");
@@ -641,15 +633,13 @@ static void gldriver_init_common(void) {
     // ----------------------------
     // setup static OpenGL state
 
-    // Depth test will always be enabled
-    glEnable(GL_DEPTH_TEST);
-
-    // We will always cull back faces for better performance
-    glEnable(GL_CULL_FACE);
-
-    // Always use this clear color
     glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
 
+    // Set up to do blending of texture quads.  Disabling DEPTH/CULL appears to fix blended quad/texture rendering on
+    // finicky Tegra 2.  This generally appears to be the correct way to do it accoring to NVIDIA forums and:
+    // http://www.learnopengles.com/android-lesson-five-an-introduction-to-blending/
+    glDisable(GL_DEPTH_TEST);
+    glDisable(GL_CULL_FACE);
     glEnable(GL_BLEND);
     glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
 
@@ -687,6 +677,17 @@ static void _gldriver_shutdown(void) {
 
     mdlDestroyModel(&crtModel);
 
+    // detach and delete the main shaders
+    // 2015/11/06 NOTE : Tegra 2 for mobile has a bug whereby you cannot detach/delete shaders immediately after
+    // creating the program.  So we delete them during the shutdown sequence instead.
+    // https://code.google.com/p/android/issues/detail?id=61832
+    glDetachShader(mainShaderProgram, vertexShader);
+    glDetachShader(mainShaderProgram, fragShader);
+    glDeleteShader(vertexShader);
+    glDeleteShader(fragShader);
+    vertexShader = UNINITIALIZED_GL;
+    fragShader = UNINITIALIZED_GL;
+
     glUseProgram(0);
     if (mainShaderProgram != UNINITIALIZED_GL) {
         glDeleteProgram(mainShaderProgram);
@@ -749,7 +750,7 @@ static void gldriver_render(void) {
         return;
     }
 
-    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+    glClear(GL_COLOR_BUFFER_BIT);
 #if MOBILE_DEVICE
     glViewport(viewportX, viewportY, viewportWidth, viewportHeight);
 #endif
@@ -903,7 +904,7 @@ static void gldriver_reshape(int w, int h) {
 #if USE_GLUT
 static void gldriver_init_glut(GLuint fbo) {
     glutInit(&argc, argv);
-    glutInitDisplayMode(/*GLUT_DOUBLE|*/GLUT_RGBA|GLUT_DEPTH);
+    glutInitDisplayMode(/*GLUT_DOUBLE|*/GLUT_RGBA);
     glutInitWindowSize(windowWidth, windowHeight);
     //glutInitContextVersion(4, 0); -- Is this needed?
     glutInitContextProfile(GLUT_CORE_PROFILE);