debug: reset the GL state more aggressively between quad renderings; this

helped find a few bugs such as textures not bound.

src/debug/quad.cpp

@@ -118,16 +118,6 @@ void DebugQuad::TickDraw(float deltams)
         data->initialised = 0;
     }
 
-    /* Reset GL states to something reasonably safe */
-    glMatrixMode(GL_PROJECTION);
-    glLoadIdentity();
-    glMatrixMode(GL_MODELVIEW);
-    glLoadIdentity();
-    glDisable(GL_TEXTURE_2D);
-    glClientActiveTexture(GL_TEXTURE0);
-    glBindBuffer(GL_ARRAY_BUFFER, 0);
-    glUseProgram(0);
-
     /* Prepare our quad coordinates */
     vec2i const layout(4, 3);
     data->step = vec2(2.0f, -2.0f) / (3 * layout + vec2i(1));
@@ -146,9 +136,12 @@ void DebugQuad::TickDraw(float deltams)
     GLfloat const texcoords[] = { f1, f3, f3, f2, f2, f4,
                                   f2, f4, f4, f1, f1, f3 };
 
+    ResetState();
+
 #if defined HAVE_GLBEGIN || defined USE_GLEW
     /*
      * Test #1: simple glBegin code
+     *
      * Renders an orange square.
      */
     glColor3f(0.8f, 0.5f, 0.2f);
@@ -163,11 +156,14 @@ void DebugQuad::TickDraw(float deltams)
     glEnd();
 
     Advance();
+    ResetState();
 
     /*
      * Test #2: glBegin + per-vertex coloring
+     *
      * Renders a multicolored square with varying colors.
      */
+
     glBegin(GL_TRIANGLES);
         glColor3f(f1, f2, f3);
         glVertex3f(data->aa.x, data->bb.y, 0.0f);
@@ -184,9 +180,11 @@ void DebugQuad::TickDraw(float deltams)
     glEnd();
 
     Advance();
+    ResetState();
 
     /*
      * Test #3: glBegin + texture
+     *
      * Renders an animated black-and-white distorted checkerboard.
      */
     glEnable(GL_TEXTURE_2D);
@@ -210,9 +208,11 @@ void DebugQuad::TickDraw(float deltams)
     glDisable(GL_TEXTURE_2D);
 
     Advance();
+    ResetState();
 
     /*
      * Test #4: glBegin + color in fragment shader
+     *
      * Renders a static, coloured and tiled pattern.
      */
     if (!data->shader[0])
@@ -245,9 +245,12 @@ void DebugQuad::TickDraw(float deltams)
     glUseProgram(0);
 
     Advance();
+    ResetState();
 
     /*
-     * Test #5: glBegin + pass color from vertex shader to fragment shader
+     * Test #5: glBegin + pass vertex coord from vertex shader to fragment
+     * shader for use as color information.
+     *
      * Renders a multicolored square with varying colors.
      */
     if (!data->shader[1])
@@ -258,7 +261,8 @@ void DebugQuad::TickDraw(float deltams)
             "{"
             "    float r = gl_MultiTexCoord0.x;"
             "    float g = gl_MultiTexCoord0.y;"
-            "    pass_Color = vec4(1.0 - r, 1.0 - g, r, 1.0);"
+            "    float b = gl_MultiTexCoord0.z;"
+            "    pass_Color = vec4(r, g, b, 1.0);"
             "    gl_Position = gl_Vertex;"
             "}",
 
@@ -271,28 +275,33 @@ void DebugQuad::TickDraw(float deltams)
     data->shader[1]->Bind();
     glColor3f(0.0f, 1.0f, 1.0f);
     glBegin(GL_TRIANGLES);
-        glTexCoord2f(f1, f3);
+        glTexCoord3f(f1, f2, f3);
         glVertex3f(data->aa.x, data->bb.y, 0.0f);
-        glTexCoord2f(f3, f2);
+        glTexCoord3f(f4, f2, f1);
         glVertex3f(data->bb.x, data->bb.y, 0.0f);
-        glTexCoord2f(f2, f4);
+        glTexCoord3f(f3, f1, f4);
         glVertex3f(data->bb.x, data->aa.y, 0.0f);
 
-        glTexCoord2f(f2, f4);
         glVertex3f(data->bb.x, data->aa.y, 0.0f);
-        glTexCoord2f(f4, f1);
+        glTexCoord3f(f4, f3, f2);
         glVertex3f(data->aa.x, data->aa.y, 0.0f);
-        glTexCoord2f(f1, f3);
+        glTexCoord3f(f1, f2, f3);
         glVertex3f(data->aa.x, data->bb.y, 0.0f);
     glEnd();
+    glEnd();
     glUseProgram(0);
 
     Advance();
+    ResetState();
 
     /*
      * Test #6: glBegin + apply texture in fragment shader
+     *
      * Renders an animated black-and-white distorted checkerboard with a
      * zoom ratio twice the one in test #3.
+     *
+     * Note: there is no need to glEnable(GL_TEXTURE_2D) when the
+     * texture lookup is done in a shader.
      */
     if (!data->shader[2])
         data->shader[2] = Shader::Create(
@@ -311,7 +320,6 @@ void DebugQuad::TickDraw(float deltams)
             "}");
     data->shader[2]->Bind();
     glColor3f(0.0f, 1.0f, 1.0f);
-    glEnable(GL_TEXTURE_2D);
     glBindTexture(GL_TEXTURE_2D, data->texture[0]);
     glBegin(GL_TRIANGLES);
         glTexCoord2f(f1, f3);
@@ -329,13 +337,14 @@ void DebugQuad::TickDraw(float deltams)
         glVertex3f(data->aa.x, data->bb.y, 0.0f);
     glEnd();
     glUseProgram(0);
-    glDisable(GL_TEXTURE_2D);
 
     Advance();
+    ResetState();
 #endif
 
     /*
      * Test #7: vertex buffer + per-vertex coloring
+     *
      * Renders a multicolored square with varying colors.
      */
     GLfloat const vertices1[] = { data->aa.x, data->bb.y, 0.0f,
@@ -356,9 +365,11 @@ void DebugQuad::TickDraw(float deltams)
     glDisableClientState(GL_COLOR_ARRAY);
 
     Advance();
+    ResetState();
 
     /*
      * Test #8: vertex buffer + per-vertex coloring + texture
+     *
      * Renders a multicolored square with varying colors multiplied with an
      * animated distorted checkerboard.
      */
@@ -386,9 +397,11 @@ void DebugQuad::TickDraw(float deltams)
     glDisable(GL_TEXTURE_2D);
 
     Advance();
+    ResetState();
 
     /*
      * Test #9: vertex buffer + texture & color in 1.10 fragment shader
+     *
      * Renders a multicolored square with varying colors xored with an
      * animated distorted checkerboard.
      */
@@ -420,6 +433,8 @@ void DebugQuad::TickDraw(float deltams)
                                   data->aa.x, data->aa.y, 0.0f,
                                   data->aa.x, data->bb.y, 0.0f };
 
+    glBindTexture(GL_TEXTURE_2D, data->texture[0]);
+
     glEnableClientState(GL_VERTEX_ARRAY);
     glEnableClientState(GL_COLOR_ARRAY);
     glEnableClientState(GL_TEXTURE_COORD_ARRAY);
@@ -435,9 +450,11 @@ void DebugQuad::TickDraw(float deltams)
     glUseProgram(0);
 
     Advance();
+    ResetState();
 
     /*
      * Test #10: vertex buffer + texture & color in 1.20 fragment shader
+     *
      * Renders a multicolored square with varying colors xored with an
      * animated distorted checkerboard.
      */
@@ -476,6 +493,8 @@ void DebugQuad::TickDraw(float deltams)
                                   data->aa.x, data->aa.y, 0.0f,
                                   data->aa.x, data->bb.y, 0.0f };
 
+    glBindTexture(GL_TEXTURE_2D, data->texture[0]);
+
     glBindVertexArray(data->array[0]);
 
     glBindBuffer(GL_ARRAY_BUFFER, data->buffer[0]);
@@ -505,9 +524,11 @@ void DebugQuad::TickDraw(float deltams)
     glUseProgram(0);
 
     Advance();
+    ResetState();
 
     /*
      * Test #11: vertex buffer + texture & color in 1.30 fragment shader
+     *
      * Renders a multicolored square with varying colors xored with an
      * animated distorted checkerboard.
      */
@@ -546,6 +567,8 @@ void DebugQuad::TickDraw(float deltams)
                                   data->aa.x, data->aa.y, 0.0f,
                                   data->aa.x, data->bb.y, 0.0f };
 
+    glBindTexture(GL_TEXTURE_2D, data->texture[0]);
+
     glBindVertexArray(data->array[1]);
 
     glBindBuffer(GL_ARRAY_BUFFER, data->buffer[3]);
@@ -575,6 +598,24 @@ void DebugQuad::TickDraw(float deltams)
     glUseProgram(0);
 
     Advance();
+    ResetState();
+}
+
+void DebugQuad::ResetState()
+{
+    /* Reset GL states to something reasonably safe */
+    glMatrixMode(GL_PROJECTION);
+    glLoadIdentity();
+    glMatrixMode(GL_MODELVIEW);
+    glLoadIdentity();
+
+    glEnable(GL_TEXTURE_2D);
+    glBindTexture(GL_TEXTURE_2D, 0);
+    glClientActiveTexture(GL_TEXTURE0);
+    glDisable(GL_TEXTURE_2D);
+
+    glBindBuffer(GL_ARRAY_BUFFER, 0);
+    glUseProgram(0);
 }
 
 void DebugQuad::Advance()

src/debug/quad.h

@@ -34,6 +34,7 @@ protected:
     virtual void TickDraw(float deltams);
 
 private:
+    void ResetState();
     void Advance();
 
     DebugQuadData *data;