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/*
* Copyright (C) 2015 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "renderstate/TextureState.h"
#include "Caches.h"
#include "utils/TraceUtils.h"
#include <GLES3/gl3.h>
#include <memory>
#include <SkCanvas.h>
#include <SkBitmap.h>
namespace android {
namespace uirenderer {
// Width of mShadowLutTexture, defines how accurate the shadow alpha lookup table is
static const int SHADOW_LUT_SIZE = 128;
// Must define as many texture units as specified by kTextureUnitsCount
const GLenum kTextureUnits[] = {
GL_TEXTURE0,
GL_TEXTURE1,
GL_TEXTURE2,
GL_TEXTURE3
};
TextureState::TextureState()
: mTextureUnit(0) {
glActiveTexture(kTextureUnits[0]);
resetBoundTextures();
GLint maxTextureUnits;
glGetIntegerv(GL_MAX_COMBINED_TEXTURE_IMAGE_UNITS, &maxTextureUnits);
LOG_ALWAYS_FATAL_IF(maxTextureUnits < kTextureUnitsCount,
"At least %d texture units are required!", kTextureUnitsCount);
glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
}
TextureState::~TextureState() {
if (mShadowLutTexture != nullptr) {
mShadowLutTexture->deleteTexture();
}
}
/**
* Maps shadow geometry 'alpha' varying (1 for darkest, 0 for transparent) to
* darkness at that spot. Input values of 0->1 should be mapped within the same
* range, but can affect the curve for a different visual falloff.
*
* This is used to populate the shadow LUT texture for quick lookup in the
* shadow shader.
*/
static float computeShadowOpacity(float ratio) {
// exponential falloff function provided by UX
float val = 1 - ratio;
return exp(-val * val * 4.0) - 0.018;
}
void TextureState::constructTexture(Caches& caches) {
if (mShadowLutTexture == nullptr) {
mShadowLutTexture.reset(new Texture(caches));
unsigned char bytes[SHADOW_LUT_SIZE];
for (int i = 0; i < SHADOW_LUT_SIZE; i++) {
float inputRatio = i / (SHADOW_LUT_SIZE - 1.0f);
bytes[i] = computeShadowOpacity(inputRatio) * 255;
}
mShadowLutTexture->upload(GL_ALPHA, SHADOW_LUT_SIZE, 1, GL_ALPHA, GL_UNSIGNED_BYTE, &bytes);
mShadowLutTexture->setFilter(GL_LINEAR);
mShadowLutTexture->setWrap(GL_CLAMP_TO_EDGE);
}
}
void TextureState::activateTexture(GLuint textureUnit) {
LOG_ALWAYS_FATAL_IF(textureUnit >= kTextureUnitsCount,
"Tried to use texture unit index %d, only %d exist",
textureUnit, kTextureUnitsCount);
if (mTextureUnit != textureUnit) {
glActiveTexture(kTextureUnits[textureUnit]);
mTextureUnit = textureUnit;
}
}
void TextureState::resetActiveTexture() {
mTextureUnit = -1;
}
void TextureState::bindTexture(GLuint texture) {
if (mBoundTextures[mTextureUnit] != texture) {
glBindTexture(GL_TEXTURE_2D, texture);
mBoundTextures[mTextureUnit] = texture;
}
}
void TextureState::bindTexture(GLenum target, GLuint texture) {
if (target == GL_TEXTURE_2D) {
bindTexture(texture);
} else {
// GLConsumer directly calls glBindTexture() with
// target=GL_TEXTURE_EXTERNAL_OES, don't cache this target
// since the cached state could be stale
glBindTexture(target, texture);
}
}
void TextureState::deleteTexture(GLuint texture) {
// When glDeleteTextures() is called on a currently bound texture,
// OpenGL ES specifies that the texture is then considered unbound
// Consider the following series of calls:
//
// glGenTextures -> creates texture name 2
// glBindTexture(2)
// glDeleteTextures(2) -> 2 is now unbound
// glGenTextures -> can return 2 again
//
// If we don't call glBindTexture(2) after the second glGenTextures
// call, any texture operation will be performed on the default
// texture (name=0)
unbindTexture(texture);
glDeleteTextures(1, &texture);
}
void TextureState::resetBoundTextures() {
for (int i = 0; i < kTextureUnitsCount; i++) {
mBoundTextures[i] = 0;
}
}
void TextureState::unbindTexture(GLuint texture) {
for (int i = 0; i < kTextureUnitsCount; i++) {
if (mBoundTextures[i] == texture) {
mBoundTextures[i] = 0;
}
}
}
} /* namespace uirenderer */
} /* namespace android */
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