/*

     File: Debug.c

 Abstract: 

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 */

#include <OpenGLES/ES1/gl.h>

#include <OpenGLES/ES1/glext.h>

#include "Debug.h"

// Debug utility: validate the current texture environment against MBX errata.

// Assert if we use a state combination not supported by the MBX hardware.

void validateTexEnv(void)

{

    #if DEBUG

    typedef struct {

        GLint combine;

        GLint src[3];

        GLint op[3];

        GLint scale;

    } Channel;

    typedef struct {

        GLint enabled;

        GLint binding;

        GLint mode;

        Channel rgb;

        Channel a;

        GLfloat color[4];

    } TexEnv;

    // MBX supports two texture units

    TexEnv unit[2];

    GLint active;

    int i, prev = -1;

    glGetIntegerv(GL_ACTIVE_TEXTURE, &active);

    for (i = 0; i < 2; i++)

    {

        glActiveTexture(GL_TEXTURE0+i);

        unit[i].enabled = glIsEnabled(GL_TEXTURE_2D);

        glGetIntegerv(GL_TEXTURE_BINDING_2D, &unit[i].binding);

        glGetTexEnviv(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE,  &unit[i].mode);

        glGetTexEnviv(GL_TEXTURE_ENV, GL_COMBINE_RGB,       &unit[i].rgb.combine);

        glGetTexEnviv(GL_TEXTURE_ENV, GL_SRC0_RGB,          &unit[i].rgb.src[0]);

        glGetTexEnviv(GL_TEXTURE_ENV, GL_SRC1_RGB,          &unit[i].rgb.src[1]);

        glGetTexEnviv(GL_TEXTURE_ENV, GL_SRC2_RGB,          &unit[i].rgb.src[2]);

        glGetTexEnviv(GL_TEXTURE_ENV, GL_OPERAND0_RGB,      &unit[i].rgb.op[0]);

        glGetTexEnviv(GL_TEXTURE_ENV, GL_OPERAND1_RGB,      &unit[i].rgb.op[1]);

        glGetTexEnviv(GL_TEXTURE_ENV, GL_OPERAND2_RGB,      &unit[i].rgb.op[2]);

        glGetTexEnviv(GL_TEXTURE_ENV, GL_RGB_SCALE,         &unit[i].rgb.scale);

        glGetTexEnviv(GL_TEXTURE_ENV, GL_COMBINE_ALPHA,     &unit[i].a.combine);

        glGetTexEnviv(GL_TEXTURE_ENV, GL_SRC0_ALPHA,        &unit[i].a.src[0]);

        glGetTexEnviv(GL_TEXTURE_ENV, GL_SRC1_ALPHA,        &unit[i].a.src[1]);

        glGetTexEnviv(GL_TEXTURE_ENV, GL_SRC2_ALPHA,        &unit[i].a.src[2]);

        glGetTexEnviv(GL_TEXTURE_ENV, GL_OPERAND0_ALPHA,    &unit[i].a.op[0]);

        glGetTexEnviv(GL_TEXTURE_ENV, GL_OPERAND1_ALPHA,    &unit[i].a.op[1]);

        glGetTexEnviv(GL_TEXTURE_ENV, GL_OPERAND2_ALPHA,    &unit[i].a.op[2]);

        glGetTexEnviv(GL_TEXTURE_ENV, GL_ALPHA_SCALE,       &unit[i].a.scale);

        glGetTexEnvfv(GL_TEXTURE_ENV, GL_TEXTURE_ENV_COLOR, &unit[i].color[0]);

        if (unit[i].enabled == 0) continue;

        if (unit[i].mode != GL_COMBINE) continue;

        // PREVIOUS on unit 0 means PRIMARY_COLOR.

        if (i == 0)

        {

            int j;

            for (j = 0; j < 3; j++)

            {

                if (unit[i].rgb.src[j] == GL_PREVIOUS)

                    unit[i].rgb.src[j] = GL_PRIMARY_COLOR;

                if (unit[i].a.src[j] == GL_PREVIOUS)

                    unit[i].a.src[j] = GL_PRIMARY_COLOR;

            }

        }

        // If the value of COMBINE_RGB is MODULATE, only one of the two multiplicands can use an ALPHA operand.

        rt_assert(!(unit[i].rgb.combine == GL_MODULATE &&

                   (unit[i].rgb.op[0] == GL_SRC_ALPHA || unit[i].rgb.op[0] == GL_ONE_MINUS_SRC_ALPHA) &&

                   (unit[i].rgb.op[1] == GL_SRC_ALPHA || unit[i].rgb.op[1] == GL_ONE_MINUS_SRC_ALPHA)));

        // If the value of COMBINE_RGB is INTERPOLATE and either SRC0 or SRC1 uses an ALPHA operand, SRC2 can not be CONSTANT or PRIMARY_COLOR or use an ALPHA operand.

        rt_assert(!(unit[i].rgb.combine == GL_INTERPOLATE &&

                   (unit[i].rgb.op[0] == GL_SRC_ALPHA || unit[i].rgb.op[0] == GL_ONE_MINUS_SRC_ALPHA ||

                    unit[i].rgb.op[1] == GL_SRC_ALPHA || unit[i].rgb.op[1] == GL_ONE_MINUS_SRC_ALPHA) &&

                   (unit[i].rgb.op[2] == GL_SRC_ALPHA || unit[i].rgb.op[2] == GL_ONE_MINUS_SRC_ALPHA ||

                    unit[i].rgb.src[2] == GL_CONSTANT || unit[i].rgb.src[2] == GL_PRIMARY_COLOR)));

        // If the value of COMBINE_RGB is INTERPOLATE and SRC0 and SRC1 are CONSTANT or PRIMARY COLOR, SRC2 can not be CONSTANT or PRIMARY_COLOR or use an ALPHA operand.

        rt_assert(!(unit[i].rgb.combine == GL_INTERPOLATE &&

                  ((unit[i].rgb.src[0] == GL_CONSTANT      && unit[i].rgb.src[1] == GL_CONSTANT) ||

                   (unit[i].rgb.src[0] == GL_PRIMARY_COLOR && unit[i].rgb.src[1] == GL_PRIMARY_COLOR)) &&

                   (unit[i].rgb.op[2] == GL_SRC_ALPHA || unit[i].rgb.op[2] == GL_ONE_MINUS_SRC_ALPHA ||

                    unit[i].rgb.src[2] == GL_CONSTANT || unit[i].rgb.src[2] == GL_PRIMARY_COLOR)));

        // If the value of COMBINE_RGB is DOT3_RGB or DOT3_RGBA, only one of the sources can be PRIMARY_COLOR or use an ALPHA operand.

        rt_assert(!((unit[i].rgb.combine == GL_DOT3_RGB || unit[i].rgb.combine == GL_DOT3_RGBA) &&

                    (unit[i].rgb.src[0] == GL_PRIMARY_COLOR || unit[i].rgb.op[0] == GL_SRC_ALPHA || unit[i].rgb.op[0] == GL_ONE_MINUS_SRC_ALPHA) &&

                    (unit[i].rgb.src[1] == GL_PRIMARY_COLOR || unit[i].rgb.op[1] == GL_SRC_ALPHA || unit[i].rgb.op[1] == GL_ONE_MINUS_SRC_ALPHA)));

        // If the value of COMBINE_RGB is SUBTRACT, SCALE_RGB must be 1.0.

        rt_assert(!(unit[i].rgb.combine == GL_SUBTRACT && unit[i].rgb.scale != 1));

        if (unit[i].rgb.combine != GL_DOT3_RGBA)

        {

            // If the value of COMBINE_ALPHA is MODULATE or INTERPOLATE, only one of the two multiplicands can be CONSTANT.

            rt_assert(!(unit[i].a.combine == GL_MODULATE    &&  unit[i].a.src[0] == GL_CONSTANT && unit[i].a.src[1] == GL_CONSTANT));

            rt_assert(!(unit[i].a.combine == GL_INTERPOLATE && (unit[i].a.src[0] == GL_CONSTANT || unit[i].a.src[1] == GL_CONSTANT) && unit[i].a.src[2] == GL_CONSTANT));

            // If the value of COMBINE_ALPHA is SUBTRACT, SCALE_ALPHA must be 1.0.

            rt_assert(!(unit[i].a.combine == GL_SUBTRACT && unit[i].a.scale != 1));

        }

        // The value of TEXTURE_ENV_COLOR must be the same for all texture units that CONSTANT is used on.

        if (unit[i].rgb.src[0] == GL_CONSTANT ||

           (unit[i].rgb.src[1] == GL_CONSTANT && unit[i].rgb.combine != GL_REPLACE) ||

           (unit[i].rgb.src[2] == GL_CONSTANT && unit[i].rgb.combine == GL_INTERPOLATE) ||

           (unit[i].rgb.combine != GL_DOT3_RGBA &&

           (unit[i].a.src[0] == GL_CONSTANT ||

           (unit[i].a.src[1] == GL_CONSTANT && unit[i].a.combine != GL_REPLACE) ||

           (unit[i].a.src[2] == GL_CONSTANT && unit[i].a.combine == GL_INTERPOLATE))))

        {

            if (prev >= 0)

                rt_assert(!(unit[prev].color[0] != unit[i].color[0] ||

                            unit[prev].color[1] != unit[i].color[1] ||

                            unit[prev].color[2] != unit[i].color[2] ||

                            unit[prev].color[3] != unit[i].color[3]));

            prev = i;

        }

    }

    glActiveTexture(active);

    glCheckError();

    #endif /* DEBUG */

}